LithosAnanake/FABRIC.md

FABRIC.md — the Stadium

Status: Living working document. Started 3 August 2026 and appended to as work proceeds. Sections are marked DECIDED, LEANING, or OPEN so they can be argued with rather than inherited.

How to read it. §1–15 are the original design argument, written before any code was examined. §16 onward are findings and decisions made against the actual tree, in the order they happened. Where the two disagree, the later section wins — earlier text is left standing, with a pointer, because §19.4 and §19.5 quote it directly and because retracing the reasoning matters more than a tidy read.

On the name. The thing described here is the Stadium. "The arena" was the working name until it collided with src/starkernel/vm/arena.c — the PMM-backed VM page allocator, an unrelated structure. The document has been swept; "arena" now survives only inside block quotes that reproduce an earlier section verbatim, and in §12's preserved question list, which several sections quote.

§25 is the punch list. It is the authoritative statement of what is done and what is not. Read its instructions before doing any work against this document.

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1. The claim

StarshipOS currently has four subsystems that each independently implement the same physics: Artemis heats blocks, Hermes ages messages, Console heats dirty cells, ACLs carry heat and TTL. Four implementations, one pattern.

The claim is that this is one mechanism wearing four costumes, and that the dictionary is already the reference implementation of it. Lift the dictionary one level of abstraction and every subsystem becomes an instance rather than a special case.

The argument that decides it: they already have the same wires. Blocks felt different because they are large and live on disk — but size and location are not properties, they are payload details. Strip those away and a block has exactly what a message has.

DECIDED. Direction is not optional. The remaining question is effort, not validity.

Updated by §20 and §17.5. There are five patron kinds, not four — VMs are the fifth and were already implemented (§20.1). And the Console's patron is the dirty event, not the cell (§17.5); "Console heats dirty cells" above is the reading that §9 flagged as suspect and §17.5 resolved.

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2. The Stadium

A single region of memory, outside any VM, holding everything currently live.

• Bounded capacity. The bound is real and inescapable.
• Allocated at boot, before any VM exists.
• Not part of the heap.

Corrected after §19.1. This bullet originally read "the bound is what gives K≡1.0 a fixed denominator. Without a hard outer wall, K is bookkeeping rather than a conservation law." That justification does not survive the definition of K.

§19.1 establishes K as a conserved, normalised heat share summing to 1.0. Its denominator is 1.0 by definition; capacity does not enter it, and §19.2 says outright that mass never enters K. A transfer-based sum is equally conserved at three patrons or three hundred — population is not what makes the check meaningful.

The bound is still necessary, for two reasons this section can honestly claim:

• Finite state (§13). A bounded population is what makes induction over the Stadium straightforward and puts model checking alongside theorem proving. This is the larger payoff and it does depend on the wall.
• Density needs a volume. §19.2 defines density as heat ÷ mass, and mass is cells occupied. Without a fixed capacity there is nothing for a patron to be dense within, and §19.3's admission rule — admit if denser than the least dense resident — has no meaning because nothing is ever full.

What makes conservation falsifiable is the mechanism, not the bound: heat that is transferred can drift and be caught; heat that is renormalised cannot. See §20.2.

The critical scoping decision, and the one that keeps this from sprawling:

The Stadium holds what is live. Not everything that exists.

DECIDED.

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3. The entry

One structure. No variants, no type field, no subclassing.

Wire	Meaning
identity	handle or name — never a content hash while resident (§24.4)
heat	conserved share of 1.0, moved by traffic (§19.1)
TTL	remaining lifetime — messages and ACLs only (§17.1)
pin	invariance flag (opposite of TTL, not an extension of it)
link	index into the Stadium, not a pointer
code field	behaviour tag from a closed enumeration (§18.3)
mass	cells this patron occupies — its footprint (§19.2)
payload	carried in the patron's own cells; large patrons are simply heavy (§23.1)
contains	index of the patron currently held inside this one, or none — containment, not a lock (§8, item 1.1)

Fixed-size cells. Links are indices, so the Stadium stays an array — no fragmentation, and tractable for Isabelle later.

A cell is one of exactly two things

The wire table above describes a patron header. §23.1 establishes that a large patron is not held by reference but simply occupies more cells — a 1024-byte block is 17 cells, one header and sixteen of payload. Those sixteen carry no identity, no heat, no TTL and no code field.

That is a second cell shape, and this section's opening line — "One structure. No variants" — forbade it without saying so. Declared properly:

A cell is either a patron header or a continuation cell owned by exactly one patron. The union is closed, two-valued, and fixed at build time.

This introduces no new principle. It is the same discipline §18.3 applies to behaviours: a closed enumeration fixed at build time is as tractable in HOL as a single record, and a two-valued union is the smallest possible instance of one. §13's "one datatype" remains true in substance — the datatype is now a two-constructor sum rather than a single record, which costs a case split and nothing else.

What it is not is a type field. The engine does not ask a header what kind of patron it is; the two-valued distinction is structural, tells the engine only whether a cell begins a patron or continues one, and is exhausted by that. A continuation cell is never ranked, never reaped and never dispatched — it is floor space, accounted for in its owner's mass.

Amended by §19.2 and §23.1. mass is an eighth wire, added when density was defined — density is heat ÷ mass, so mass has to live in the entry. And the original payload rule ("inline if small, by reference if large") was dissolved rather than answered: a large patron occupies more cells, which is what mass already measures. By-reference is reserved for things outside the Stadium, which are not patrons.

Amended again by item 1.1 (§25.2). contains is a ninth wire — an index to the patron currently held inside this one, or none. This does not reopen the two-valued cell union above: the contained patron keeps its own independent header and cells elsewhere in the Stadium, resolved and ranked exactly as any other patron. contains is a reference to that residency, not a physical embedding of one patron's cells inside another's. See §8 for what this wire is for and why it replaced a lock.

Amended by item 3.1 (2026-08-04) — the header/continuation discriminator is an external side bitmap, not a header field. A flat-array scan must tell a header cell from a continuation cell before it knows which shape it is looking at. That rules out folding a tag into either variant's own bytes: a continuation cell has no header fields to place one in, and forcing a common leading tag byte into both shapes would eat into the continuation cell's usable payload, contradicting §23.3's 60-byte figure. Ruled: one bit per cell, in a bitmap kept outside the 64-byte cell array. Item 3.1 declares the bitmap's purpose and indexing; item 3.2 (boot-time allocation) allocates it, since it is Stadium-sized memory decided at boot alongside the cell array itself.

The code field is the entire type system. A block's code field migrates. A message's delivers. A VM's ticks. The engine never asks what kind of thing it is holding; it heats, ranks, reaps, and calls the code field.

If you find yourself wanting a type field so the engine can branch on entry kind, the design has gone wrong. The code field already answers that question.

DECIDED, including the payload question — dissolved in §23.1.

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4. Heat

Heat is conferred by traffic, not intrinsic to the entry.

This is the piece that was missing for most of the session. Nothing decides what matters. An entry is hot because activity is concentrated around it — the way a crowd in front of one car makes that corner of the hall hot. Density generates heat; nobody computes it.

Consequences:

• Ranking is read, not decided. There is no scheduler because there is no policy. The Stadium is simply already in heat order when you look at it.
• K constrains the total, so ordering is forced by conservation rather than by tuned parameters. There is nothing to tune wrongly. This is the defensible distinction from a scheduler and it belongs in the write-up.
• Popularity is self-limiting. A crowded entry is harder to reach, which throttles traffic to it, which cools it. The governor is local and emergent — no global damping constant to pick.

TTL expiry stays unconditional: entries leave at their own time, unscheduled, nobody's decision. Pinning remains the separate, opposite mechanism — invariance, not longevity.

DECIDED as amended by §19. The density formulation this section called for is supplied there. Three specific amendments, and the original wording above is left intact because §19.4 and §19.5 quote it:

• "Density generates heat" is backwards (§19.5). Traffic confers heat; density is heat ÷ mass, derived downstream. One word was carrying two meanings.
• The third bullet is struck, not repaired (§19.4). "A crowded entry is harder to reach" does not translate — a hot entry is easier to reach, which is what a cache is for. The conclusion survives via the second bullet: heat is zero-sum, so popularity is self-limiting by conservation.
• The first bullet is now true rather than aspirational. Ranking reads density, which §19.2 makes a number.

The line about TTL and pinning is correct but incomplete — §17.1 shows there are three departure mechanisms, not two: TTL, heat decay, and pin.

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5. What is not in the Stadium

This section exists because forcing everything in is how this design turns into a mess.

• Storage is beneath the Stadium. The show floor is not the warehouse. Artemis is where entries live when they are not in play. Blocks migrate onto the floor when hot and back out when cold — which is heat-driven block migration, already built. Artemis does not become a Stadium occupant; it becomes what the Stadium pages against.
• Devices are beside the Stadium. The framebuffer is the building's lighting, not an occupant. Console's dirty events are Stadium entries; the pixels are not.

DECIDED, and completed by §17.5, which supplies the third edge this section counted but did not list, and sharpens the second:

Category	Relation	Example
Warehouse	beneath	Artemis, and the dictionary (§17.3)
Stadium	the floor	patrons
Utility	beside	framebuffer, and devices generally

"The building's lighting" undersells the framebuffer — it reads as part of the structure. §17.5 calls it the power company: external infrastructure the building consumes. Not the Stadium, not the basement of the Stadium, a third thing.

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6. Boot order

The engine cannot be a VM service, because VMs live inside the thing it manages.

1. LithosAnanke establishes the Stadium and starts the engine.
2. Hera becomes the first entry in it.
3. Hera births everything else, sizing each VM as it goes.

Structurally the same move as minting Zuse's certificate at first boot: a root that cannot be produced by the mechanism it grounds.

DECIDED. The order was right, and the allocation mechanism this section left unspecified is now given: one global array of fixed-size cells, sized at boot from the memory budget, addressed by index (§17.6b, §22.3). Step 1 above allocates that array before any VM exists; step 2 makes Hera the first patron in it (§20).

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7. Hera

Hera's job becomes Stadium distribution. This is not a new responsibility — allocating a VM's share is birthing it, and lifecycle is already what Hera is for.

OPEN: RESOLVED in §22 — elastic. Whether a VM's share is a hard bound or an elastic one that can grow and shrink under pressure, with capacity transferring between VMs as a conserved operation Hera arbitrates. Elastic is more powerful and more work. Under elasticity, birth sizes the rest volume rather than a cap — a more forgiving thing to have to guess right.

§22 takes the elastic option. §19's density definition turns it into a negative feedback loop that runs itself — capacity flows down the density gradient — so it costs less than this section anticipated. The layout that makes it cheap is a single global cell pool with per-VM quotas held as counts (§22.3), and capacity must move on a slower loop than heat (§22.4).

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8. The mental model

An auto show hall.

Cars and people, in a building with a fixed capacity. People arrive and leave at their own times. They ask questions and converse — those are the messages. They stand in front of a car for a while and move on. Occasionally one sits in a car, which is the only exclusive thing in the room, scoped to a single object, no global lock.

The hall gets crowded. Crowds get hot.

One discipline to hold: cars and people cannot be two structures. That would be a type field re-entering through a metaphor. They are one entry shape differing only in TTL and code field — a car's lifetime is the show, a person's is a visit; a car's code field is be attended to, a person's is move and attend.

RESOLVED by item 1.1 (§25.2), 2026-08-04. "Occasionally one sits in a car, which is the only exclusive thing in the room, scoped to a single object, no global lock." The instinct that this needs an exclusivity primitive was right; the instinct that it needs a lock was not. Sitting in a car is not mutual exclusion — it is containment. The person-patron does not get barred from the car-patron; it goes inside it.

The mechanism is the ninth wire, contains (§3): an index to the patron currently held inside this one, or none. Getting in sets it; getting out clears it. The contained patron keeps its own independent header and residency — it is still ranked, still heats and cools like anything else — contains only records the relationship.

Reap is gated, not derived. A patron with a non-none contains link cannot be reaped. This is checked ahead of density ranking, as an absolute rule, not inferred from mass or density — a light, cold container with something inside it must not read as evictable just because the numbers say so. This is what actually answers the use-after-free concern §9 raised: the engine cannot select an occupied patron for reaping in the first place.

Containment chains, and unwinding is forced, not chosen. Because a patron can itself be contained, contains links can form a chain — a patron inside a patron inside a patron. If A contains B contains C, A cannot become reapable until B is empty, and B cannot become reapable until C departs. This ordering is topological, not a policy — there is no FIFO/LIFO choice to make here; the chain's own shape forces innermost-first.

Bounded, single occupant per level. Each patron holds at most one contains link (single occupant, not a set). Chain depth is capped — default 5 — enforced by the engine at containment-entry time (refuse to nest past the cap). The cap is a Kconfig symbol, not a hardcoded constant, consistent with this project's existing tunable-knob convention (STARFORTH_ENABLE_VM, HOTWORDS_CACHE_SIZE, etc.) — named at implementation time in item 3.1, default 5, scannable via menuconfig.

What this leaves genuinely open, deferred, not blocking: if multiple independent containment chains are simultaneously blocked and waiting to unwind, whether the engine gives any of them priority over another is a scheduling question, not a header-design one. It does not affect the wire, the reap gate, or the depth cap, and is left for whenever it becomes a real concern.

§22.3's earlier remark that separate-region layout gives "physical fault containment" that the single-cell-pool layout gave up is unaffected by this — contains is a logical reference within one VM's own Stadium, the same trust boundary that layout decision already accepted.

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9. The admission test

Before writing code, run this on paper against every candidate entry type. Two questions, both of which must have a non-forced answer:

1. What does heat mean for this thing?
2. What is its reap event?

COMPLETE. Run against every candidate; all five patron kinds pass, and the two ? marks are closed:

Type	Heat means	Governed by	Reap is	Verdict
Block	accessed often	heat decay	migration back to Artemis	passes
Message	delivery urgency	TTL	delivery	passes
VM	runs often	heat decay	death by cooling	passes (§20)
Word	executed often	heat decay	cooling off the floor	passes (§17.3)
ACL	checked often	TTL	expiry (§17.1)	passes
Screen cell	—	—	—	not a patron (§17.5)

Screen cells were the suspect case and the suspicion was correct. A cell never expires — it is a fixed grid position always present, so cells-as-entries would leave most of the Stadium inert and permanently pinned. §17.5 confirms the reading anticipated here: the patron is the dirty event, not the cell. The grid stays outside, and the event turns out to be a message with a different destination rather than a sixth kind.

Words were added to the table by §17.3 — the original list omitted them because §1 treated the dictionary as the reference implementation rather than as a population of patrons.

Ten minutes on paper. It confirmed the design and caught one case, which is what it was for.

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10. Sequencing

FABRIC.md first, then Hermes native on the fabric, then measure, then Console, then Artemis last.

Amended by §16.5 and §21.2. This ordering is still right for the subsystems, but it is not the first work. A substrate floor sits beneath all of it: Hera alone, real timer interrupts and a real IRQ return path on all three ISAs (§16.1), and compudynamics driven from that tick. None of the sequencing below can begin until that exists, because the engine has nothing to run on. §25 carries the actual order.

Reasoning:

• Hermes is unfinished, which is lucky. Finishing it the old way and refactoring later means deliberately writing code already slated for deletion. Build it on the fabric directly and it carries zero migration debt.
• It becomes the proving ground — the fabric gets tested against a real subsystem before anything that currently works is touched.
• It produces the effort number empirically. What Hermes costs is the multiplier for everything else. One data point from real work beats any amount of estimating.
• Artemis reads, writes, and persists reliably today. That is banked. It goes last, because it is the thing you cannot afford to break.

Existing instrument: the POST suite exercises every dictionary word and was already earmarked as the regression gate for the shrink-to-colon-definitions pass. Same tool, second job.

Caution: a green POST suite does not mean K still holds. Those are different claims. The DoE campaign validated K on the current substrate; changing the substrate means re-running it. Automated, but budget for it.

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11. Where the debt accrues

• Dual paths — avoidable, and the big one. Never two live heat mechanisms at once. Convert one subsystem completely, prove it, move on. Every shim bridging old and new is debt, and new code will get written against whichever is convenient.
• Speculative generality — avoidable. Only add a wire when a second entry type needs it. Generality that never pays back is still debt.
• The exception — not avoidable, so decide it early. If one subsystem does not fit and gets special-cased, that special case is permanent and worse than not unifying: you carry the general machinery and the exception, and every future reader learns both. This is why the admission test comes before code.

Early signal: ARTEMIS.md, HERMES.md, CONSOLE.md and TRIPOD.md each currently describe their own heat mechanics. After FABRIC.md, each should shrink to roughly three lines — what an entry is here, what heat means, what the reap event is. If any one of them gets longer, that subsystem is fighting the fabric, and you will know which one before writing code.

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12. Open questions — five closed, one partial

Status as of §24. Five of the six are answered or dissolved; Q5 is partial. The original text is kept below because several later sections quote it.

	Question	Outcome	Where
Q1	Payload threshold	dissolved — large patrons are simply heavy	§23.1
Q2	Entry header size	sized — 64-byte cell, ~32-byte header (constants to validate)	§23.3
Q3	Screen cell or dirty event	event; the grid is not a patron	§17.5
Q4	Per-VM share hard or elastic	elastic, via quota over one pool	§22
Q5	Loop coupling / timescales	partly — capacity must move slower than heat	§22.4
Q6	One region or nested per VM	nested, two levels	§21

Q5 is marked partly deliberately: §22.4 fixes the one ordering that matters (capacity slower than heat) but the full eight-loop interference analysis has not been done, and §16.1 notes it cannot be until a real time base exists on all three ISAs.

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1. Payload threshold — what size goes inline versus by reference.
2. Arena entry header size. Cardinality spans orders of magnitude (dozens of VMs, thousands of messages, potentially very many screen events). The header must be sized for the worst case, and that case is the screen. Sizing this constrains everything else, so settle it early.
3. Screen cells: entry-per-cell or entry-per-dirty-event. (Leaning: event.)
4. Per-VM share — hard bound or elastic under pressure.
5. Loop coupling. Roughly eight feedback loops once Hera and heartbeat depth are counted. The algorithms are known; the risk is interference. Usual discipline is separation of timescales — keep nested loop periods an order of magnitude apart. Cheaper to decide than to debug.
6. Whether the arena is one region for the whole system or nested per VM. Nested implies K conserved at each level with messages as the only thing crossing a boundary, which would mean no shared-memory atomicity is ever needed. Single region is simpler but reintroduces locking — the one mechanism this architecture has otherwise never wanted.

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13. What this does to formal verification

This may be the largest payoff, and it was not the reason for the change.

Verifying four subsystems means four state models, four conservation arguments, and — the expensive part — proofs about how they interact. That last category grows combinatorially and is where a verification effort usually dies. Unification deletes it outright.

What the design gives Isabelle/HOL, more or less for free:

• One datatype. The Stadium entry is a single record. Everything else is payload. You reason about entry once rather than about blocks, messages, VMs and events separately. (Amended by §3: a cell is a two-constructor sum — patron header or continuation cell — not a bare record. That costs one case split and nothing else; the point stands.)
• No pointers. Fixed-size cells with index links means the Stadium models as a total function over a finite index set — no heap model, no separation logic, no aliasing, no null. This is the single biggest difference between a tractable proof effort and a research project.
• Finite state. Bounded capacity means the state space is finite. Induction over the Stadium is straightforward, and model checking becomes available alongside theorem proving.
• One conservation theorem. Every engine operation preserves K. Proved once against the engine, it holds for every entry kind — because the engine cannot distinguish them. Previously this was four proofs plus their interactions.
• A clean model boundary. Storage below and devices beside the Stadium means disk I/O and framebuffer writes sit outside the model, at the C primitive boundary already drawn.
• A trivial initial state. Boot order — kernel, then Stadium, then engine, then Hera — gives a base case that is trivially conserving, with everything else following by induction on operations.

One constraint this imposes, and it is not optional.

The code field is late-bound behaviour, which is the one part of this that HOL does not like: an arbitrary function stored in a record is higher-order and can wreck termination arguments. The fix is a design rule rather than a proof technique:

The set of code-field behaviours must be a closed enumeration, fixed at build time.

Model it as a datatype of behaviour tags plus a dispatch function and the whole thing stays first-order and tractable. Leave the code field open as a general extension point and you have traded four easy verification problems for one genuinely hard one.

This is consistent with the existing rule that adding a primitive requires rebuilding from source rather than doing it from inside a running system. Worth stating explicitly in the fabric design, because it is the kind of constraint that gets casually violated later by someone adding "just one" dynamic behaviour.

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14. Formalism

The thermodynamic analogy holds in places and inverts in one, which matters for the paper but not for the build.

• Fixed capacity → closed system. K≡1.0 → conservation. Capacity transfer → work. These map cleanly.
• Heat is not entropy. Heat is closer to energy or temperature. Entropy would measure how heat is distributed: concentrated is low, uniform is high.
• This matters practically. K is conserved, so K can never tell you anything — it is 1.0 by construction, a correctness check rather than a diagnostic. Entropy over the heat distribution actually varies, and distinguishes idle from productive from thrashing. That is the real instrument, and the quantity worth driving the LED matrix with.
• The inversion: the second law says entropy rises spontaneously. This system does the opposite — it self-organizes, concentrating heat where work happens. That is not equilibrium thermodynamics; it is a driven dissipative system, order sustained by throughput. Prigogine, not Carnot. A stronger claim, but only if stated correctly — writing "thermodynamic system" while entropy decreases unprompted is an easy shot for a reviewer.

Phenomenon first, then mathematics. The formalism follows the phenomenon; it does not gate the build, and it is not finished until it is correct.

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15. The whole thing in five lines

• The Stadium holds the live crowd. Storage is the warehouse. Devices are the utility.
• One entry shape. The code field is the only difference between kinds.
• Traffic confers heat. Heat is conserved at 1.0. Density is heat per cell. Ranking reads density.
• Departure is TTL, or cooling, or never. Pinning is invariance, not longevity.
• The kernel opens the hall. Hera walks in first, and cannot be asked to leave.

(Amended from the original five by §17.5, §19.5, §17.1 and §20.5 #3. The earlier third line — "heat is density, conferred by traffic" — conflated two quantities; the earlier fourth — "departure is unconditional" — knew only one mechanism.)

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16. Substrate findings — 2026-08-03

Naming: the arena is now called the Stadium, because src/starkernel/vm/arena.c already owns "arena" for the PMM-backed VM page allocator — an unrelated concept. The document has since been swept to the new name, and §1–15's substance reconciled against §16–24 with each superseded claim marked in place.

Four findings from reading the tree. The first three change what step one costs. The fourth changes what the engine is allowed to be.

16.1 There is no interrupt return path on two of three ISAs

The engine has to be driven from outside the VMs (§6), which in a kernel means interrupts. That mechanism does not currently exist on most of our targets.

• apic_timer_start() is an explicit no-op stub on aarch64 (arch/aarch64/apic.c:82) and riscv64 (arch/riscv64/apic.c:76). Both say the driver is deferred.
• heartbeat_tick() is defined on all three architectures and called from exactly one site in the tree: arch/amd64/interrupts.c:337. On the other two it is dead code.
• Worse: every vector in arch/aarch64/isr.S — IRQ included — is a bare branch to a handler that prints and enters for(;;) wfe. arch/riscv64/isr.S is the same shape. There is no register save, no ERET, no SRET.

So enabling a timer interrupt today halts the kernel on the first tick. The work is not "write a timer driver," it is "build the interrupt return path that was never built."

Consequence for §12 Q5. That question assumes a hierarchy of loop periods kept an order of magnitude apart. Separation of timescales presupposes a time base. There is one real time source, on one architecture; everything else paces off execution count. Q5 cannot be answered on the current substrate — it is downstream of this work, not parallel to it.

16.2 riscv64's time base is a guess

arch/riscv64/timer.c:46 sets s_counter_hz = 1000000000ULL with the comment /* assume 1 GHz */. The file header concedes rdcycle's frequency is not architecturally discoverable.

Every heartbeat variance and TIME-TRUST figure riscv64 has produced was computed against a wrong expected_delta. This has to be fixed as part of any timer work, and it means riscv64 timing numbers before and after that fix are not comparable.

16.3 The dictionary is already a Stadium

§1 claims the dictionary is the reference implementation. It is stronger than that — but not as strong as an earlier draft of this subsection claimed. Read against DictEntry (include/vm.h:335-351):

§3 wire	In DictEntry	Form
identity	word_id + name[]	correct
heat	execution_heat + physics	correct
TTL	acl_ttl	correct
pin	acl_pinned, plus WORD_PINNED / WORD_FROZEN	correct
link	struct DictEntry *link	a pointer, not an index
code field	word_func_t func	a raw function pointer, not an enumerated tag
mass	—	absent
payload	— (definition body lives outside the entry)	absent

Four wires present in correct form, two present in the wrong form, two absent. An earlier draft said "six of eight" and named the missing two as mass and a behaviour tag, which double-counted the code field and omitted payload.

The wrong-form pair is the interesting part. link being a pointer is precisely what §13 identifies as "the single biggest difference between a tractable proof effort and a research project," and the raw function pointer is what §18.3 requires to become a closed tag.

So the honest claim is weaker than "the dictionary is a Stadium entry" and still strong enough to carry §1: the dictionary already has the concepts, and two of the eight need to change form. Everything else is what gets generalised toward it.

But run §9's admission test on it before moving it in. Its reap event is the weak wire. Blocks migrate, messages deliver, VMs die by cooling — a dictionary word does not expire. Heat decays to a floor and the word stays; FORGET is manual and rare. That is the same shape §9 already flags as suspect for screen cells: hundreds of permanently resident, largely inert entries. It may well be fine, but the dictionary is too central to wave through, and it is precisely the case §9 exists to catch.

Also: the dictionary is what parity.c hashes. Moving its representation into the Stadium changes that hash, so every committed baseline in logs/ shifts. Not a blocker — but a deliberate re-baseline with a before/after record, not something to discover later.

16.4 The engine must stay deterministic — this is a new constraint

Nothing in §1–15 says this, and it binds the engine tightly.

parity.c logs a dictionary hash per VM birth. The DoE's 0.000% CV across 90 runs and the patent support material both rest on the same capsule producing the same heat state on every run. Today that holds for a reason worth naming: ticking is execution-driven. vm_tick() (vm/vm_runtime.c:114) is called from execution paths, and its own header says "Synchronous (now): Called from main execution loop, every N executions." Same instruction sequence, same tick points, same decay events, same hash.

Wall-clock ticking does not have that property. Under TCG, elapsed time varies run to run on identical input.

The interrupt may supply pacing, but the engine must fire on tick count, never on elapsed wall time.

Same input → same tick ordinal → same reap and inference events → same hash. This keeps parity intact while still letting compudynamics be genuinely timer-driven.

There is a second, narrower version of the same discipline. heartbeat_tick() measures inter-tick deltas to derive variance and TIME-TRUST. If the engine's own work ran inside that handler, the handler's runtime would become part of the interval it measures — the instrument would be reporting the cost of running the instrument. So the interrupt does bookkeeping only; the engine runs outside it. The split already exists in the tree and works: adaptive_check_accumulator / adaptive_pending (include/vm.h:113-114), set at rolling_window_of_truth.c:372-375, serviced at :1302-1308.

DECIDED unless argued — it is a constraint inherited from what the system already claims, not a new preference.

Corrected by the GAP-A1 ruling — the tick is virtual

The rule above ("fire on tick count, never on elapsed wall time") was necessary but not sufficient, and its inference — same tick ordinal → same hash — was unsound. The hash covers execution_heat, which is co-written by two streams: word executions and engine ticks. A hardware timer makes the interleaving of those streams wall-clock-dependent under TCG, so same-per-tick actions do not compose into the same hash. See §25.7.1 GAP-A1 for the full argument.

RULED 2026-08-03:

The engine's tick is a virtual tick — a pure, deterministic function of the execution stream. This is what exists today (vm_tick() paced every N executions) and it is why parity holds today. The hardware heartbeat is the TIME-TRUST instrument, the idle wake source, and the driver of nothing that feeds patron state. When the system is idle, the REPL poll loop pumps virtual ticks so TTLs still expire in real time — a context in which parity was never claimed.

Phase 0's timer bring-up remains fully justified: it makes the instrument real on three ISAs instead of one, and it is the substrate SMP will eventually need. What it does not do is drive the engine.

Whatever step one turns out to be, it now has a floor under it: real timer interrupts and a real IRQ return path on all three ISAs. §10's sequencing (Hermes first, as the proving ground) sits above that floor, not below it.

---

17. Patrons

An occupant of the Stadium is a patron. Blocks, words, ACLs, messages and VMs are all patrons. The word is doing real work: it names the category without implying a class hierarchy, and it keeps the metaphor honest — patrons attend, they are not the building.

VMs were omitted when this section was written and added by §20, which found they were already implemented as the outer level. Five kinds, not four — the counts elsewhere in §17 predate that and should be read accordingly.

DECIDED.

17.1 Patrons die several different ways — and that is not a type field

The observation that prompted this section is correct: these things do not all end the same way. A message is consumed. An ACL lapses. A block should never be destroyed. A word should never be destroyed either.

The reflex is a decision branch on patron kind. That is the type field §3 forbids, and it is not needed — but neither is the opposite over-simplification, which an earlier draft of this section made and which is corrected here.

Heat and TTL are not the same mechanism, and neither is a special case of the other. §3 lists them as separate wires and they must stay separate. A message carries a countdown. A block does not — a block leaves the floor because it cooled, not because a timer expired. Collapsing the two forces the design, which is precisely the failure §11 warns about.

There are three mechanisms, and each patron uses the ones that genuinely apply:

Mechanism	Nature	Patrons	Departure
TTL	countdown to a definite event	messages, ACLs	expiry
Heat decay	continuous, gradual	blocks, words	cooling off the floor
Pin	invariance — §3's wire	any	never

Mapped per patron:

Patron	Governed by	Reap event
Message	TTL	delivery — consumed, gone
ACL	TTL	expiry
Block	heat decay	migration back to Artemis — evicted, not destroyed
Word	heat decay	cooling off the floor (see §17.3)
VM	heat decay	death by cooling (see §20); Hera is pinned (§20.5 #3)

Two measures, one clock

This does not mean two clocks. Both mechanisms advance off the same tick — the virtual tick of §16.4 as ruled, a deterministic function of the execution stream, not the hardware heartbeat. TTL decrements on a tick; heat decays on a tick. They are two different readings of one counter, not two independent time sources.

That is not a tidiness preference, it is forced — twice over. §16.4 requires the engine to fire deterministically so the same input reproduces the same dictionary hash. And the mechanisms cannot be split across clocks: TTL expiry has side effects on the instruction stream (a message expiring versus delivered changes what runs next), so a wall-clock TTL would corrupt heat downstream even if heat itself stayed execution-paced. One virtual clock for everything that touches patron state; the hardware heartbeat observes and wakes, never drives.

One tick. Two measures. Three mechanisms.

The engine still asks nothing about patron kind. It advances the tick, applies whichever measures a patron carries, and calls the code field when a patron departs. A pinned patron never departs. There is no type interrogation — see §18 for how the dispatch works without one.

17.2 Reaping is not destruction

The block case is the one that makes this work, and §9 already had it right: a block's reap event is migration. §5 puts storage beneath the Stadium, with blocks coming onto the floor when hot and going back off when cold.

So a block is reaped in exactly the sense the engine means — it leaves the floor. Where it goes afterwards is the code field's business, not the engine's. A message's code field ends in delivery; a block's ends in a write-back to Artemis. Same event, different behaviour, no special case.

This is worth stating plainly because "reap" reads as "free" and here it does not:

Reap means leaves the floor. It does not mean destroyed.

DECIDED.

17.3 Words: the dictionary is the warehouse, hot words are the patrons

§16.3 left words as the unresolved patron. Pinning all of them resolves nothing — several hundred permanently resident, largely inert entries is the §9 screen-cell failure with a different label, and it wastes the bounded capacity that density needs as its volume (§19.2; this sentence originally cited the K-denominator justification that §2's correction removed — D1).

The better reading applies §5 unchanged. Storage sits beneath the Stadium. The full dictionary sits beneath it too, and only hot words are on the floor.

This is not speculative — it already exists and is already measured:

• src/physics_hotwords_cache.c maintains the hot-word set
• cache_hits_delta is column 4 of the DoE CSV, "hot-words cache hits this tick"
• execution heat (Loop #1) is what promotes a word; linear decay (Loop #3) is what cools it

So the hot-word population is already a live, moving crowd with an existing promotion rule and an existing cooling rule. It is the crowd. The dictionary is the warehouse it is drawn from, exactly as Artemis is the warehouse blocks are drawn from.

The existing cache is only half-aligned — and that is the argument for doing this

Reading physics_hotwords_cache.c closely turns up something that strengthens the case rather than weakening it. Heat governs admission to the cache. Nothing governs departure.

hotwords_cache_promote() (:362-383), when full, writes the new word to cache[lru_index] and advances that index modulo the size. That is round-robin. The field is named lru_index, the inline comment at :365 says "LRU eviction: remove oldest entry (round-robin)", and the doc block at :347 says "round-robin least-recently-used" — which is a contradiction in terms. Nothing anywhere tracks recency of use. Promotion is gated on execution_heat > HOTWORDS_EXECUTION_HEAT_THRESHOLD (:283); eviction consults heat not at all.

The consequence is that the hottest word in the cache can be evicted purely because its slot came up in the rotation.

That is a direct contradiction of §4:

Ranking is read, not decided. There is no scheduler because there is no policy. The Stadium is simply already in heat order when you look at it.

Round-robin eviction is exactly a policy — an arbitrary one, uninformed by the physics the rest of the system runs on.

This is the strongest practical argument for §17.3. Moving words onto the Stadium is not a relabeling exercise; it repairs a real defect by deleting the arbitrary half of an existing mechanism. And it is measurable before and after: stats.evictions, stats.promotions and stats.cache_hits are already instrumented and already flow into the DoE CSV.

Consequences if this holds:

• Words need no pin exception. Their reap event is cooling off the floor — the same shape as a block's, one level up.
• §16.3's objection dissolves. The dictionary does not move into the Stadium wholesale; it stays beneath it and pages against it.
• The parity concern in §16.3 narrows considerably. The dictionary's own representation is not what changes — what becomes a patron is the hot set, which is already transient.
• Pin stops being a general-purpose escape hatch and goes back to meaning what §3 says: invariance, for the few things that genuinely must not vary.

LEANING. The mechanism is already built and the fit is clean, but this reframes a direction stated differently earlier the same day, and it deserves longer than a paragraph.

17.4 Open

1. What is a word's TTL, concretely? DISSOLVED — a word has no TTL. The premise was wrong. §17.1 (as corrected) establishes TTL and heat decay as two distinct mechanisms, not one clock read two ways: words are governed by heat decay, and only messages and ACLs carry a TTL. Nothing needed unifying and no second mechanism was required.

2. Is the hot-word set bounded today? RESOLVED — yes, hard bounded. DictEntry *cache[HOTWORDS_CACHE_SIZE] (include/physics_hotwords_cache.h:168) is a fixed array inside the struct, with HOTWORDS_CACHE_SIZE = 32 (:84). Nothing is allocated — hotwords_cache_cleanup() notes there is nothing to free, since the cache holds borrowed pointers the dictionary owns. It is per-VM (vm->hotwords_cache, used at dictionary_management.c:320), not global. This is exactly the inescapable outer wall §2 requires.

   Two things follow. First, the bound is 32 out of a 453-word Mama dictionary — a very tight floor. Whether that is the right Stadium population or an artifact of the structure having been sized as a lookup cache rather than as a live set is a design input, not a given. Second, the eviction defect in §17.3 above.

   Reported, not fixed: in hotwords_cache_promote(), if word is NULL and the cache is full, the guard at :363 falls into the inner branch at :364 and writes NULL into cache[lru_index]. Unreachable today — every caller passes a non-NULL entry from the bucket search — but the NULL check reads as though it prevents this, and does not.

3. ACL reap RESOLVED — TTL expiry. ACL entries already carry acl_ttl in DictEntry, so they fall under the TTL mechanism in §17.1 alongside messages. §9's ? is closed.

4. Does a patron ever change what it is? RESOLVED in §24 — and the question was slightly wrong. Full immutability is not available: FORTH blocks mutate in place by definition (BLOCK / UPDATE / FLUSH), while words already behave the opposite way, redefinition creating a new entry. The kinds genuinely disagree.

   What actually mattered was never payload but mass and identity. §24.2 states the invariant: identity never changes during a residency; mass never changes as a side effect of use; header fields mutate freely; payload contents may mutate provided size and identity do not. That gives §13 the enumerable mass function it needed without demanding immutability nothing could deliver.

17.5 The framebuffer is not a patron — it is a utility

DECIDED. This is §5 and §2 applied rather than a new call, but it was close enough to becoming an exception that it is worth writing down explicitly.

Outside the Stadium is not the same as an exception

§11's warning is about a patron kind that needs special handling inside the engine — you end up carrying the general machinery and the carve-out, and every future reader has to learn both. That is the thing to fear, and the fear is correct.

But §5 is not a carve-out. It is a taxonomy. The test for whether something is an exception is: does the engine change because this thing exists? For the framebuffer, nothing changes. The engine never learns about it. That is a boundary, not an exception.

It fails §2's liveness test by definition, not by fiat

§2's scoping decision is the sharpest line in this document: the Stadium holds what is live, not everything that exists. A patron arrives and departs. The framebuffer does neither — it is there from init to power-off. It has no arrival event and no reap event, not because it has been excused from having them, but because it genuinely has none.

Better than "the building's lighting": a utility

§5 calls the framebuffer the building's lighting, which undersells it — that reads like part of the structure. It is closer to the power company: external infrastructure the building consumes. Not the Stadium. Not the basement of the Stadium. A third thing.

That gives three categories, all principled, none of them exceptions:

Category	Relation	Example
Warehouse	beneath	Artemis, the dictionary (§17.3)
Stadium	the floor	patrons
Utility	beside	framebuffer, and devices generally

What is live is the dirty event — and it is not a new patron kind

(Written when the taxonomy had four kinds; §20 has since added VMs as the fifth. The point stands unchanged — the dirty event adds nothing to the taxonomy at all.)

Run §9's two questions on it:

• Heat means — a region written often is hot. A scrolling log, a blinking cursor. A static border is cold. Traffic confers heat, identically to everything else.
• Reap is — redraw. Consumed by being painted.

Consumed on delivery, carries a TTL, dies on arrival. A dirty event is a message whose recipient happens to be the framebuffer. It does not extend the patron taxonomy; it is the message patron with a different destination.

Which yields a symmetry worth keeping:

Patron	Code field terminates at	Which lives
Block	Artemis	beneath
Dirty event	framebuffer	beside

Both are code fields finishing outside the Stadium. Neither is special.

This closes the last ? in §9. The screen-cell row resolves to: the event is the patron, the grid is not.

The sizing argument, independently

A framebuffer is several megabytes of fixed device memory. Making it a patron means either swamping the bounded capacity (§2) — as mass, it would dwarf every other patron and make density comparisons meaningless — or forcing a by-reference payload path to exist for exactly one pathological object, which §23.1 has since abolished for patrons entirely. Sizing a design around its single largest outlier is how the header ends up wrong for the other ten thousand entries. (This paragraph originally leaned on the K-denominator justification removed from §2 and on the pre-§23.1 payload framing; the conclusion is unchanged — D1.)

Not a patron does not mean no physics

Worth stating so it is not lost: excluding the framebuffer from the Stadium says nothing about whether compudynamic concepts apply within it. A utility can have its own internal dynamics — heat over regions, decay, adaptive refresh — without being a Stadium participant. The power company has physics too.

OPEN, deferred. What those dynamics are is a question for when the framebuffer work actually happens. It does not gate the Stadium, and it should not be designed speculatively now.

17.6 Sizing and allocation — the Stadium should be dynamic, but not heap-allocated

§3 says the Stadium stays an array with index links. That is right, but it is stated in a way that invites the wrong objection, because "array" and "fixed at compile time" are not the same thing — and it is the second one that is genuinely objectionable.

A hardcoded capacity is arbitrary: HOTWORDS_CACHE_SIZE = 32 is a number someone picked, and §17.4 shows exactly how that ages. A contiguous block of fixed-size cells, sized at boot from the memory budget and addressed by index, is dynamic in every sense that matters operationally while remaining an array in every sense §3 and §13 depend on.

Four positions, with what each costs:

	What it is	Cost
a	Capacity fixed at compile time	Arbitrary bound. What the hot-words cache does today.
b	Sized at boot, contiguous, index-linked	None. Retains every property below.
c	Contiguous but resizable at runtime	K's denominator moves; couples to §7
d	Per-entry allocation, pointer links	Forfeits §13

Why (b) is free

The Stadium is established before any VM exists (§6), so boot is already the moment its capacity is determined. Deriving that capacity from available memory rather than from a constant costs nothing and gives up nothing. Cells stay uniform, links stay indices, the region stays contiguous.

SUPERSEDED by §22.3 — the answer is (b) with a refinement. The Stadium is one global array of cells sized at boot, and per-VM shares are quotas held as counts rather than separate regions. That keeps (b)'s properties while making (c)'s elasticity trivial, so the two are no longer alternatives.

Why (d) is expensive — by this document's own argument

§13 is unambiguous:

No pointers. Fixed-size cells with index links means the Stadium models as a total function over a finite index set — no heap model, no separation logic, no aliasing, no null. This is the single biggest difference between a tractable proof effort and a research project.

Per-entry heap allocation gives that up and takes several things with it:

• The finite state space. Bounded capacity is what makes induction over the Stadium straightforward and what puts model checking on the table alongside theorem proving.
• §2's hard outer wall. The bound is what gives density a volume to be dense within (§19.2) and §13 its finite index set. (This bullet originally read "Without an inescapable bound, K is bookkeeping — §2 says this in as many words"; §2 no longer says that, and §20.2 established conservation is falsifiable regardless of the bound — D1.)
• The engine's simplicity. This is a freestanding kernel with kmalloc.c / pmm.c and no libc. Allocation in the reap path means the engine can fail to allocate, which means the engine needs a failure mode, which means it is no longer the thing §3 describes. An engine that can fail is a different engine.

Fragmentation is the least of it, though §3 is right that indices avoid that too.

Why (c) is the genuinely open one

A contiguous region that grows and shrinks as a whole keeps index links and keeps the proof structure — the capacity becomes a parameter rather than a constant, which HOL handles without difficulty. What it complicates is K, since the denominator moves.

This is not a new question. §7 already has it open for per-VM shares: "whether a VM's share is a hard bound or an elastic one that can grow and shrink under pressure, with capacity transferring between VMs as a conserved operation Hera arbitrates." Elasticity at the Stadium level and elasticity at the per-VM level are the same question asked at two scales, and they should be answered together rather than separately.

OPEN RESOLVED — and the prediction here was right. Q6 did resolve to nested (§21), and (c) did become the attractive option (§22). But §22.3 found a cheaper route to it than resizing a contiguous region: with quotas held as counts over one shared cell pool, elasticity costs arithmetic on two integers and the denominator never moves at the level that matters. The total stays fixed; only the partition shifts.

The rule this reduces to

Dynamic in capacity. Static in structure.

Decide how big the Stadium is at runtime. Do not decide what an entry is, or how entries are addressed, at runtime.

---

18. The engine — L0

The engine that holds the patrons is a loop like the others, and it needs a name in the same scheme. L1–L7 are taken by the existing feedback loops; L8 is the Jacquard mode selector. The engine sits beneath all of them, so: L0.

18.1 L0 and L8 bookend the gated loops

This produces a structure worth drawing, because it explains why two of the ten are different in kind:

  L8   Jacquard mode selector      always on, ungated
  ─────────────────────────────────────────────────────
  L1 … L7   feedback loops         gated by L8
  ─────────────────────────────────────────────────────
  L0   the Stadium engine          always on, ungated

L1–L7 are gated: L8 switches them on and off, 128 configurations over seven bits.

The two bookends are ungated, and for symmetric reasons:

• L8 cannot be gated because something has to decide the gates. A selector that could deselect itself has no defined behaviour.
• L0 cannot be gated because it is what holds the patrons the other loops operate on. Switch it off and nothing is reaped, the Stadium fills and stays full, and K stops being conserved. That is not a mode, it is a failure state.

This is the same argument §6 makes about boot order. The thing that manages existence cannot be a participant in what it manages — not for VMs, and not for loops.

DECIDED.

18.2 The Jacquard accounting is an exclusion, not an extension

The obvious reading of "add L0" is that the selector grows a bit: 7 bits becomes 8, 128 configurations become 256.

That is the wrong move, and §18.1 is why. L0 is not gateable, so it has no bit. The gate word stays seven bits wide and the selector stays at 128 states.

This is worth stating explicitly because the alternative is expensive: widening the gate word would invalidate the 128-configuration L8 table, the DoE campaign already run against it, and the existing results. There is no reason to pay that, and the design does not ask us to.

L0 is accounted for in Jacquard by being deliberately absent from it.

DECIDED.

18.3 Dispatch: enumerate behaviours, not kinds

§13 already requires a closed enumeration:

The set of code-field behaviours must be a closed enumeration, fixed at build time… Model it as a datatype of behaviour tags plus a dispatch function and the whole thing stays first-order and tractable.

So a fixed enum with fixed dispatch is mandatory, not a concession to practicality. But there are two things one could enumerate, and only one of them preserves §3:

	Enumerate	Engine asks	Cost of a new patron kind
✗	patron kinds — BLOCK, WORD, ACL, MESSAGE, VM	"what are you?"	touch the engine
✓	behaviours — MIGRATE, DELIVER, EXPIRE, COOL	nothing; calls dispatch(tag)	none

This was not hypothetical. VMs were added as a patron kind by §20 after this section was written, and cost the engine nothing — a VM's behaviour tag is COOL, the same tag a word carries. Under the rejected column it would have been an engine change.

Both are closed, both are fixed at build time, both are equally provable. Only the second keeps the engine ignorant of its contents, which is the property §3 exists to protect. Two patrons may share a tag; a new patron that migrates costs zero engine changes.

The branching Captain Bob is right to want is real and it is allowed — it lives in the dispatch function over a closed tag set, not in the engine asking patrons what they are.

DECIDED.

18.4 One tick

L0 advances on the virtual tick — a deterministic function of the execution stream, per the §16.4 ruling. Everything derived from time is derived from that one counter:

• TTL decrements per tick (messages, ACLs)
• Heat decays per tick (blocks, words)

Two measures, one clock — see §17.1. §16.4 as ruled forces this: patron state must advance deterministically for the same input to reproduce the same dictionary hash, and the hardware heartbeat cannot supply that, because its interleaving with the instruction stream is wall-clock-dependent. The heartbeat's roles are the TIME-TRUST instrument and the idle wake source; when the system idles, the REPL poll loop pumps the virtual tick.

18.5 CLOSED — the adaptive rate does not break determinism, and here is why

The concern: the heartbeat is adaptive — faster, slower, window wider, narrower. If it adapts off timing measurements, the adaptation is machine-dependent and §16.4 fails. If it adapts off execution-derived state, tick ordinals still map deterministically to work and parity survives.

Traced end to end on 2026-08-03. The dictionary-parity chain is clean. Resolution (1) — adaptation inputs are execution-derived, TIME-TRUST stays diagnostic — is already the de-facto design.

Evidence, in the order it decides the question:

1. TIME-TRUST is computed and never consumed. heartbeat_trust() has zero callers in the entire tree. m5_time_trust and m5_variance (include/vm.h:315-316) are declared and never read or written. The only consumer of ts->trust is starkernel/doe_log.c:98, which writes it to a CSV column. It is measured and reported, never fed back.

2. The intent is already documented. include/starkernel/timer.h:70 — "TIME-TRUST thresholds in Q48.16 (for diagnostics, NOT for gating)."

3. Every inference-engine input is execution-derived. vm_runtime.c:626-640 populates InferenceInputs from: the rolling window, trajectory_length (from window_pos / total_executions), prefetch_hits / prefetch_attempts, hot_word_count, stale_word_count, total_heat, word_count, and the previous check's baselines. No timing input of any kind. The outputs it applies — adaptive_window_width and adaptive_decay_slope — therefore depend only on execution history.

4. Decay is tick-based, and deliberately so. vm_tick_apply_background_decay() is handed vm_monotonic_ns(vm) but computes elapsed_ticks = tick_count - last_decay_tick (vm_runtime.c:375). The now_ns argument only writes last_decay_ns. The comment at :373-374 says so explicitly: "Tick-based, not wall-clock… now_ns is kept only to refresh last_decay_ns for diagnostics." Someone already defended this exact boundary.

5. The parity hash contains nothing time-derived. capsule_dict_hash_hook() (capsule/capsule_vm_hooks.c:60-70) walks the dictionary hashing exactly two things per entry: the word name and execution_heat. Not last_decay_ns, not any timestamp. So even the diagnostic wall-clock field from (4) cannot reach the hash.

Conclusion: §16.4 holds today, and holds by construction rather than by luck.

One real exception, and it is not in the parity path

vm_physics_touch() (capsule/capsule_vm_physics.c:250-313) is wall-clock dependent: it computes elapsed_us = (now_ns - last_active_ns) / 1000 (:272) and the header comment at :122 confirms the transfer amount scales with elapsed time. So fleet-level VM heat is not reproducible run to run the way dictionary heat is.

Scope of that, precisely:

• It touches node->physics in the VM registry, not DictEntry.execution_heat, so it does not reach the parity hash and does not invalidate the existing claim.
• vm_physics_tick() (:366) explicitly discards its now_ns argument ((void)now_ns;), so only the touch path is affected.
• With Hera alone this is nearly inert. It becomes live again when Hermes and Artemis return.

This is a pre-existing condition, not something the Stadium introduces. But it is exactly the pattern L0 must not inherit, and it is worth knowing that fleet K figures and dictionary parity have different reproducibility guarantees today.

The invariant this should become

Determinism currently survives on convention plus one good comment. That is too thin for something load-bearing. L0 should make it explicit:

Anything that influences patron state advances on tick count. Wall-clock time may be recorded for diagnostics and must never be an input to a decision.

DECIDED, and it supersedes the "leaning (1)" in the earlier draft of this section.

---

19. Mass, density, and what K actually is

§4 is marked LEANING with the note that "the density formulation needs a concrete definition." This section supplies it. It is the keystone: §4 claims ranking is read rather than decided, and that claim is empty until the thing being read is a number.

The objection that forced this section is the right one. Density is quantity per unit volume, so it implies a mass and a volume. Neither had been named.

19.1 K is already defined, and it is not an occupancy ratio

This has to come first, because the obvious definition of K contradicts working code.

vm_physics_conserved() (capsule/capsule_vm_physics.c:456-461) sums execution_heat_q48 across live VMs and tests that total against Q48_ONE:

uint64_t sum  = vm_physics_fleet_heat_sum();
uint64_t diff = (sum > Q48_ONE) ? (sum - Q48_ONE) : (Q48_ONE - sum);
return diff < VM_PHYSICS_EPSILON_Q48;

So:

K is a conserved, normalised heat share. Total heat is always 1.0. Traffic transfers heat to a patron from the others; it does not create it.

K is not occupancy, and defining it as Σmass / capacity would contradict an implemented, tested mechanism. It stays exactly as it is.

19.2 Three quantities, not one

Quantity	What it is	Range	Status
Heat	conserved share, moved by traffic	Σ = 1.0 always	already implemented
Mass	cells the patron occupies — its footprint	integer ≥ 1	new
Density	heat ÷ mass — heat per cell	derived	new

Heat is the conserved quantity. Mass is an independent axis and never enters K. Density is the ratio, and it is density in the literal sense at last: quantity per unit volume, where the volume is a patron's own footprint inside the bounded capacity §2 requires.

A patron holding a large share of the fleet's heat in a single cell is dense. A patron squatting on four cells with a negligible share is sparse, and belongs back in the warehouse.

DECIDED.

19.3 Everything else reads off it

The point of §4 is that no policy exists. With density defined, none is needed:

• Ranking — order by density. Read, not computed by a scheduler. §4's first bullet is now true rather than aspirational.
• Admission when full — admit the newcomer if it is denser than the least dense resident, and evict that one. This is a comparison of two intrinsic numbers, not a policy, and it closes the "what happens when the Stadium is full" gap.
• Hysteresis — falls out unpaid-for. A heavy patron needs a proportionally larger heat share to hold its floor space, so a block sitting near the threshold does not oscillate on and off. No damping constant to pick, which is what §4 wanted and could not previously deliver.
• Migration cost is not a separate quantity. An earlier draft of this reasoning treated cost-to-move as its own axis. It is not needed: footprint and cost correlate, because a patron is expensive to move precisely because it is large. Deriving cost from mass avoids introducing a second tunable, which §11 would rightly call speculative generality.

19.4 Correction to §4 — the self-limiting claim has the wrong mechanism

§4's third bullet states:

Popularity is self-limiting. A crowded entry is harder to reach, which throttles traffic to it, which cools it. The governor is local and emergent — no global damping constant to pick.

The conclusion is right and the mechanism is wrong. In a hall, a crowd physically blocks access to the car. In a computer the inverse is true — a hot entry is easier to reach, since that is the entire purpose of a cache. The metaphor does not survive translation, and no mechanism in this design reproduces the blocking effect because the effect is not real in this substrate.

The real governor is conservation. Heat is zero-sum: total heat is 1.0, so a patron heating up necessarily cools every other patron, and nothing can exceed the ceiling. Popularity is self-limiting because there is a fixed amount of popularity to go around.

This is §4's second bullet — "K constrains the total, so ordering is forced by conservation rather than by tuned parameters" — which was the correct answer already. The third bullet should be struck, not repaired. Designing a mechanism to make the crowd metaphor come true would be fitting the system to the analogy, which §14 already warns against in the other direction.

DECIDED. §4's third bullet is superseded by this section.

19.5 Correction to §4 — "density generates heat" reverses the causality

§4 says "Density generates heat; nobody computes it." Under §19.2 that is backwards, and the confusion is that one word was carrying two meanings:

• Traffic generates heat — activity concentrated on a patron transfers heat share to it. §4's causality is correct with this word substituted.
• Density is heat per cell — derived from heat, downstream of it, and it is the quantity that gets read when ranking.

The corrected statement:

Traffic confers heat. Heat is conserved at 1.0. Density is heat per cell. Ranking reads density.

Nobody decides what matters at any step in that chain. §4's spirit is intact; only the noun was overloaded.

19.6 Open

1. What is mass, exactly, for each patron? RESOLVED by §23.1 — the by-reference loophole is closed: if the payload is in the Stadium it counts toward mass, and what is not in the Stadium is not resident. The one residue — whether continuation cells are contiguous or linked, which shifts every large patron's mass — is §23.4 #4, scheduled as item 1.12. (D2)
2. Is mass constant for a patron's lifetime? RESOLVED by §24.3 — mass changes only through an arbitrated transfer, never through traffic, so density is stable between transfers and §13 gets a mass function that changes at enumerable points. (D2)
3. How does traffic transfer heat between patrons, concretely? vm_physics_touch() does this today for VMs, but it scales the transfer by wall-clock elapsed time (capsule_vm_physics.c:272), which §18.5 forbids for anything influencing patron state. The transfer rule must be restated on tick count before L0 can use it. This is the single most concrete piece of work this section implies.

---

20. VMs are patrons

§17 named four patrons: blocks, words, ACLs, messages. That list is incomplete, and the omission matters because the missing kind is the only one already implemented.

§9's admission table has always included VM — heat means runs often, reap is death by cooling — and §6 states it directly: "Hera becomes the first entry in it." Those cannot be reconciled with a four-patron taxonomy. VMs are patrons. Chronologically they are the first ones.

DECIDED.

20.1 This is a finding, not a proposal

The outer Stadium already exists in working code:

• vm_physics_fleet_heat_sum() sums execution_heat_q48 across live VMs, and vm_physics_conserved() tests that total against Q48_ONE (capsule/capsule_vm_physics.c:456-461).
• That is a Stadium's K, computed over VM patrons. §19.1's definition of K was derived from it.
• Hera already reaps VMs; TRIPOD.md makes governing existence her defining contract.

So the mechanism §19 describes is not novel at the VM level. It is running now.

20.2 The outer level is unbounded — but fleet K is a real conservation law

This subsection previously claimed fleet K was "bookkeeping" that could not fail. That was wrong, and it was wrong on a point of fact rather than of interpretation. It is replaced here rather than annotated. The error: it asserted heat is renormalised after population changes, without reading the paths where renormalisation would have to occur.

Heat is transferred, not renormalised

Read end to end in capsule/capsule_vm_physics.c:

• The primitive (:147-154). vm_physics_transfer() subtracts from one patron and adds the same amount to another, clamped at zero. Its own comment: "The one conservative primitive everything else is a special case of… Nothing is created or destroyed: sum(execution_heat for all LIVE VMs) is invariant across any call."
• Birth (:156-185). Hera (vm_id 0) is seeded with Q48_ONE; every other VM starts at zero, described as "cold mass added to a closed system." Population growth rescales nothing.
• Death (:225-247). The dying VM's entire heat is transferred to the root it chains up to before being zeroed.
• Touch (:250-311). Pulls from other live VMs proportionally, clamped to what they actually hold so it "can never manufacture heat."

There is no renormalisation anywhere. vm_physics_conserved() tests a genuine invariant.

It is therefore falsifiable — and there are two ways it can drift

1. A documented leak (:240-244). If a dying VM is itself the root, or its parent chain is broken, there is nowhere conservation-preserving to send the remainder and it is dropped. Both cases are guarded and described as "shouldn't happen," but the path exists.
2. Truncation (:304-305). The proportional fan-out computes (moved_total * heat) / others_total per VM in integer arithmetic. The shares sum to less than moved_total. Every multi-VM touch loses a little heat, so the sum drifts downward monotonically. VM_PHYSICS_EPSILON_Q48 is 3277 — 5% of Q48_ONE — so given enough touches this would eventually trip.

What this means for the bound, and for the campaign

Bounding the VM population does not make conservation falsifiable — it already is. The two are unrelated, and §2 has been corrected accordingly. The bound is still needed, for finite state (§13) and because density requires a capacity to be dense within (§19.2).

It also changes the reading of the Artemis campaign's K-invariance arm. That arm was not measuring an identity. It was measuring a quantity that genuinely could drift, and which did not drift far enough to trip a 5% epsilon over the run. That is a real result about the system, not an artefact of the check.

Reported, not scheduled: the truncation leak at :304-305 is a live defect in a conservation law the project makes claims about. It is small per touch and may be entirely tolerable, but it is monotonic, and nobody has measured how far it drifts over a long run.

20.3 Nesting — §12 Q6 is less open than it looks

If VMs are patrons, the structure follows without further invention:

  Outer Stadium        patrons: VMs                  ← exists today (unbounded)
    └── per-VM Stadium patrons: words, blocks,
                                ACLs, messages       ← to be built

K conserved at each level, with messages as the only thing crossing a boundary. That is precisely §12 Q6's nested option — "K conserved at each level with messages as the only thing crossing a boundary, which would mean no shared-memory atomicity is ever needed" — and the outer level is already there.

This does not close Q6 by itself, but it changes the question. The choice is no longer between two greenfield designs; it is whether to formalise a nesting that is already half built, or to collapse it into a single region and discard the level that works.

LEANING nested. DECIDED nested in §21, written immediately after this section (D3). See §20.5 for what still had to be settled.

20.4 A VM's mass is the capacity share Hera allocated it — RESOLVED by item 1.6

RESOLVED 2026-08-04. What follows was written as a proposal; it is confirmed here rather than rewritten, because everything since has already been treating it as decided. §22's elasticity mechanism (DECIDED) only means something if a VM's mass is its variable quota — "capacity flows down the density gradient" (§22.1) is vacuous if every VM's mass were pinned at one cell. §24.3 already states outright that "a VM's mass is elastic by §22." Items 1.2 through 1.5 (the resting floor, the transfer trigger, the timescale ratio, the outer bound) all already read mass-as-quota as given. §20.5 #2's own framing settles it independently: the one-cell alternative "throws away the distinction" in the table below, which is the entire reason for doing this. A VM's mass is the capacity share — the quota — Hera allocated it, not a fixed one-cell footprint regardless of size.

Decided on paper, not yet built: VMPhysics currently holds only execution_heat_q48, last_active_ns and is_live (capsule_vm_physics.c:59-63). There is no share field yet — adding one is implementation work for a later phase, not this item.

§7 says Hera's job is Stadium distribution, and that allocating a VM's share is birthing it. If that share is the VM's mass, §19's density definition applies unchanged at the outer level, and §7 stops being abstract.

The payoff is that Hera gets a strictly better lifecycle signal than heat alone:

VM	Heat	Mass	Density	Reading
small, quiet	low	low	moderate	healthy — dense enough, merely small
big, idle	low	high	low	sparse — reap or shrink
small, busy	high	low	high	dense — a candidate to grow

Heat alone cannot distinguish starved from small. Density can. TRIPOD.md states that Hera uses the fleet K view for exactly this question — "Is a child VM healthy? Is a child VM starved?" — and density is the quantity that actually answers it.

Note this stays within TRIPOD.md's constraint that fleet K is lifecycle telemetry, not a dispatch mechanism. Density informs whether a VM should exist or change size. It never decides where work goes; that remains capability-based routing.

20.5 Open

1. Bounding the VM population. RESOLVED by item 1.5 (§25.2), 2026-08-04. What is the outer Stadium's capacity, and what happens at the bound — birth refused, or coldest VM reaped?

   Correction first: "coldest reaped, consistent with §19.3" does not survive §20.2. §19.3's admission rule is admit if denser than the least dense resident. §20.2 already decided every VM but Hera is born at heat zero. A newborn can never be denser than an existing warm VM, so applying §19.3 literally at the outer level means births at the bound would fail regardless — just silently, via a comparison that can never succeed, instead of by an explicit refusal. Treating "coldest reaped" as automatic would also require a bespoke, non-density rule that exists for VMs alone, which is exactly the per-kind special case §11 warns against.

   Resolution: birth is refused at the bound. Making room is Hera's own deliberate act — she already reaps VMs (§20.1) — never an automatic side effect of someone else's birth request. This is the explicit, stated behaviour the original text asked for.

   The bound itself: 4, Kconfig-tunable, explicitly a placeholder. 4 matches Tripod's own currently-known topology (Hera + two Hermes instances + Artemis) — the smallest number that doesn't already contradict what this system is known to need, not a padded estimate. It is expected to be too small for real workloads. The right way to find an idealized default is empirical — a DoE campaign, the same discipline already used elsewhere in this project (experiments/bare_metal/) — not a second guess made on paper. Tracked as future work, not invented here. The constant is a Kconfig symbol (e.g. STADIUM_MAX_VM_COUNT, named at implementation time in item 3.1 alongside the other new symbols this phase introduces), not hardcoded.

   Fixed for the machine's lifetime once set at build — resolves §22.5 #4 below in the same stroke. The outer total does not itself flex at runtime; only per-VM quotas do (§22). An outer bound that could grow or shrink live would mean §2's "inescapable wall" is not actually inescapable.

2. Is a VM's mass its allocated share, or one cell? RESOLVED by item 1.6 — the allocated share. See §20.4.

3. What is Hera's own mass? RESOLVED — Hera is pinned, and her eviction is a panic.

   She is the first patron and she governs the rest, so she is subject to §3's pin wire: invariance, not longevity. That is the correct use of pin rather than an exception to the rules.

   But pinning alone is a silent guarantee, and a silent guarantee that fails under load is worse than none. If the engine ever selects Hera for eviction, that is a kernel panic, not a skipped iteration and not a logged warning. The condition is unreachable by construction; reaching it means the invariant is already broken and continuing would run the system without a governor.

   State it as an assertion at the eviction site, not as a filter on the candidate set — filtering hides the bug, asserting reports it.

   Her mass is still whatever §20.4 resolves for VMs generally. Pinning governs whether she can depart, not how much room she takes.

4. Does the nesting recurse further? RESOLVED by item 1.7 (§25.2), 2026-08-04. A VM's Stadium holds patrons; if one of those patrons were itself a VM, the structure is a tree rather than two levels. Nothing currently requires this, and §11 would call it speculative generality — but it should be bounded deliberately, since the boot order in §6 does not forbid it.

   Not the same question as §8's contains chains (item 1.1) — those are same-Stadium patron-holds-patron relationships, bounded to depth 5, and do not create a second Stadium. This is specifically about a patron being a VM with its own nested Stadium underneath it.

   Resolution: bounded by a Kconfig-tunable cap, default 2 — not a hard "never." Consistent with how item 1.1 treated its own depth question rather than declaring a permanent architectural prohibition. 2 matches what §21 already decided and what already exists: the outer Stadium (patrons: VMs) and each VM's own inner Stadium (patrons: words, blocks, ACLs, messages). Nothing today drives a third level, so 2 is the honest default, not a padded estimate. The cap is enforced explicitly at VM-birth time — birthing a VM whose own Stadium would sit at a depth beyond the configured cap is refused, the same "explicit refusal over silent/emergent behaviour" discipline item 1.5 used for the outer bound — rather than left as an unstated assumption nothing checks.

---

21. §12 Q6 resolved — nested

Q6: Whether the arena is one region for the whole system or nested per VM. Nested implies K conserved at each level with messages as the only thing crossing a boundary, which would mean no shared-memory atomicity is ever needed. Single region is simpler but reintroduces locking — the one mechanism this architecture has otherwise never wanted.

Resolved: nested. The conclusion Q6 leaned toward is right; the reason it gives is not.

DECIDED.

21.1 The locking premise is false — locking is already free

Every mutex in the kernel build is a no-op. src/starkernel/vm/host/shim.c:415:

void sf_mutex_lock(sf_mutex_t *mutex) {
    (void)mutex;
}

dict_lock and tuning_lock (include/vm.h:410,507) are real pthread_mutex_t in the hosted build (platform_lock.h:58-63), but the kernel compiles with -DSTARFORTH_MINIMAL=1 (Makefile.starkernel:253) and the shim stubs them out. The stated rationale is accurate: "Single-threaded kernel: no contention is possible at the VM level."

So the cost Q6 weighs against the single-region option is currently zero. The architecture has not avoided locking; it has locking, inert. Q6 cannot be decided on this basis.

21.2 Step one introduces real concurrency — and locks are the wrong answer for it

This belongs in §16's substrate work, not here, but it surfaced while resolving Q6 and it lands sooner than anything the Stadium needs.

Once the timer interrupt fires on all three ISAs (§16.1), the ISR preempts the mainline. That is genuine concurrency between two contexts sharing state on a single hart. It does not exist today, which is precisely why the no-op stub is currently safe.

Making the mutexes real would not fix it and would actively break it: on a single hart, an ISR spinning on a lock the mainline holds deadlocks outright, because the mainline can never run to release it. This is a well-known failure and it is easy to introduce by reflex.

The correct answer is already in the design — §18.4's top-half / bottom-half split:

• ISR (top half) touches only a word-sized counter and a flag. Single writer.
• Mainline (bottom half) is the only context that mutates Stadium structure.

No lock, no deadlock, and no reliance on atomicity beyond aligned word access. This is a constraint on the L0 implementation, not a preference.

Nothing in interrupt context may mutate Stadium structure. Ever.

21.3 What actually decides Q6

With locking removed from the argument, six discriminators remain:

	Nested	Single region
Matches what exists	hotwords_cache, rolling_window, dictionary are already per-VM; the physics registry is already outer	collapses a working two-level structure into one
Fault containment	a VM cannot corrupt another's Stadium	one bad patron reaches everything
Capacity transfer (§7)	meaningful — VMs have shares to trade	no per-VM share exists to transfer
K semantics	conserved per level; existing fleet K survives unchanged	fleet K needs re-deriving
Verification (§13)	prove the engine once, instantiate at both levels — demonstrates genericity	one region, marginally simpler
If SMP ever happens	messages are the only boundary-crossers → no shared memory, still no locks	needs real locks, and the no-op stubs become a live correctness hole

The last row is the strongest, and it is what Q6 was reaching for. Nested does not avoid locking today — nothing needs locking today. Nested avoids locking permanently, including in a multi-hart future where the current stubs would silently stop being correct.

The first row is the most practical: §20.1 established that the outer level already exists and works. Single-region means discarding a working structure to build a simpler one, which is a poor trade at this stage.

21.4 The shape this fixes

  Outer Stadium          patrons: VMs
    │                    K conserved here
    │                    bounded — see §20.5 #1
    │
    ├── Hera's Stadium   patrons: words, blocks, ACLs, messages
    │                    K conserved here, independently
    │
    └── (future VMs)     same shape, no special cases

Messages are the only patrons that cross a boundary. Everything else is confined to the level it was born on.

21.5 Consequences and open items

1. The no-op mutexes are now load-bearing in a way they were not before. They are correct today and correct under nesting, but only while the top/bottom discipline in §21.2 holds. That discipline should be stated in the code at the stub site, so the next reader does not "fix" the no-op into a spinlock and deadlock the kernel.
2. Two capacities to size, not one. §20.5 #1 (outer bound) and §17.6 (per-VM bound) are now distinct questions with distinct answers.
3. §12 Q4 / §7 / §17.6(c) elasticity becomes the live question. Nesting is what makes capacity transfer between VMs meaningful, so the hard-versus-elastic decision can no longer be deferred as an abstraction — it is the next real fork.
4. §20.5 #4 remains open. Nesting is two levels here. Whether a patron may itself contain a Stadium — a tree rather than two tiers — is still deliberately unruled. Nothing requires it; it should be excluded on purpose rather than by omission.

---

22. Elasticity resolved — elastic, via quota over a single cell pool

§7, §12 Q4 and §17.6(c) are one question asked at three scales: is a VM's share of capacity a hard bound, or elastic under pressure with transfer arbitrated by Hera?

Resolved: elastic. And the layout that makes it cheap is a single global cell pool with per-VM quotas, not separate physical regions.

DECIDED.

22.1 Why elastic — §19 turns it into a feedback loop

Under §19's definition, elasticity stops being a feature to implement and becomes a negative feedback loop that runs itself:

  VM gets busy  →  heat share rises  →  density rises
                →  capacity flows toward it  →  mass rises
                →  density falls back

Capacity flows down the density gradient — from sparse VMs toward dense ones. That is diffusion. There is no threshold to choose, no damping constant, and nothing decides: it is §4's read, not decided applied one level up.

A hard bound offers none of this. It offers a number that had to be guessed correctly at birth and stays wrong.

§7's own argument is the practical half, and it holds:

Under elasticity, birth sizes the rest volume rather than a cap — a more forgiving thing to have to guess right.

Predicting a VM's resting size is far easier than predicting its peak, and being wrong self-corrects instead of persisting.

22.2 The connection to §14

Heat concentrates where work happens — §14's driven-dissipative inversion, order sustained by throughput. Capacity then follows heat. So the two distributions move in opposite directions: heat concentrates while density equalises.

That makes the flatness of the density distribution a real, measurable signal of a settled system, distinct from the heat distribution's entropy that §14 already identifies as the instrument worth having. Two signals, not one, and they say different things.

22.3 The layout decision, which matters more than hard-versus-elastic

Framing this as hard-versus-elastic obscures the real choice. Elastic is cheap or expensive entirely according to how the Stadium is laid out, and §21's nesting decision does not settle that.

Layout	Elastic cost	Isolation	§13 verification
Separate physical regions	expensive — transferring capacity means moving memory, and regions fragment against each other	physical	two index spaces
One cell pool, per-VM quota	trivial — arithmetic on two integers	logical (disjoint index sets)	one index space, one total function
Separate regions, hard bounds	n/a	physical	two index spaces

Chosen: one global array of cells, one global index space. Nesting becomes a partition of that index set rather than separate allocations. A VM's quota is a count, not a contiguous range, so there is no adjacency requirement, no fragmentation, and index links keep working because indices are global.

Free lists are per-VM, not shared

An earlier draft of this section said cells are drawn from a shared free list. That was wrong, and it quietly undercut the argument that decided §21.

§21.3's decisive discriminator is the SMP row: messages are the only boundary-crossers, so no shared memory and still no locks. A shared free list is shared mutable state, touched by every VM on every admission and every reap. Under SMP it would need a lock or atomics — exactly what that row claims nesting avoids permanently. The defence offered there, that "VMs never touch each other's cells," does not reach it: the free list is nobody's cell, and allocation touches it.

The fix costs essentially nothing:

Each VM holds its own free-list head index into the global array. Hera hands a VM its cells when she grants quota; the VM allocates and frees only within what it holds.

One head index per VM instead of one global head. One index space is preserved, one datatype is preserved, §13 is unaffected — and disjointness becomes total rather than nearly total. No mutable structure is shared between VMs at all, which is what §21.3 actually promised.

Transfer of capacity is then Hera moving cells from one VM's free list to another's, which is still arithmetic plus a list splice, and still arbitrated at a known point (§22.5 #2).

Two reasons this is the right trade:

• §13 gets simpler rather than harder. One array, one datatype, one total function over one finite index set. A partition of a finite set is trivial in HOL. Separate regions would mean two of everything and a cross-region invariant to maintain.
• §21's reasoning survives intact. Its argument for nesting was K conserved per level with messages as the only boundary-crossers — both preserved. SMP-safety also survives: what matters is that VMs never touch each other's cells, and disjoint index sets give that provided quota changes are arbitrated by Hera, which §7 already requires.

What is given up is physical fault containment — a corrupt index could reach another VM's patrons where separate regions would fault instead. That was one of §21.3's six discriminators and not the decisive one. It is a real cost, recorded here rather than glossed.

22.4 Capacity moves slower than heat — required, not preferred

Two conserved quantities in motion can oscillate. Heat moves on traffic; capacity moves on density. At comparable rates they chase each other and the ratio never settles.

Heat responds tick by tick. Capacity responds to sustained density across many ticks.

This is §12 Q5's separation-of-timescales discipline — "keep nested loop periods an order of magnitude apart" — arriving as a concrete instance rather than general advice, and it partly answers Q5.

The exact ratio is a tuning question, but the ordering is not: capacity must be the slower loop. Getting this backwards produces a system that thrashes while every individual rule looks correct.

RESOLVED by item 1.4 (§25.2), 2026-08-04 — 1000:1, grounded in an existing precedent, not picked from nothing. capsule_vm_physics.c:434-441's vm_physics_heartbeat_tick() already runs a fleet-level slow loop at HEARTBEAT_INFERENCE_FREQUENCY virtual ticks (default 1000, starforth_config.h:72) to recalibrate fleet_transfer_slope_q48 — the rate vm_physics_touch() uses for heat transfers. Different mechanism (heat-transfer-rate recalibration, not capacity/mass transfer), but the identical shape item 1.3's capacity-tick needs: a coarse, fleet-level reassessment layered over the fine virtual tick, in the same file, same subsystem.

The capacity-tick gets its own named constant rather than literally sharing HEARTBEAT_INFERENCE_FREQUENCY — they are conceptually separate concerns (inference-engine window/decay tuning versus capacity arbitration), and coupling them would mean retuning one silently retunes the other. But its default is 1000, matching this precedent rather than inventing an unrelated number. 1000:1 against the virtual tick is comfortably past §12 Q5's "order of magnitude apart" minimum. Named and made a Kconfig symbol at implementation time (item 3.1), same tunable-knob convention as item 1.1's containment-depth cap.

22.5 Open

1. The resting floor. RESOLVED by item 1.2 (§25.2), 2026-08-04. A VM that goes quiet loses capacity; if it wakes it may not regain it fast enough. The obvious guard is a floor below which a quota cannot fall — but that is a tuned number, which this design otherwise avoids.

   Floor = max(mass of pinned patrons, one message-sized cell). The first term is the principled alternative this section already named: derived, not tuned. The second term closes a gap the first term leaves open on its own — a VM with zero pinned patrons would otherwise get a floor of zero, and a VM with zero quota cannot receive anything, including the message that would be the reason for it to wake up and regrow via §22.1's density-gradient feedback. That is a deadlock: no capacity to receive, no way to ever regain capacity. One message-sized cell is itself derived, from §23.3's cell sizing rule ("size the cell so a typical message is exactly one cell"), not a second tuned constant — so the discipline this section wanted to preserve still holds with both terms in place.

2. What arbitrates a transfer, concretely? RESOLVED by item 1.3 (§25.2), 2026-08-04. §7 says Hera. Under §22.3 a transfer is arithmetic on two integers, so the mechanism is trivial — but when she does it, and on what signal, is not yet stated.

   The cadence is the slow part, not a threshold. Hera evaluates the density gradient once per capacity-tick — a coarser, derived multiple of the virtual tick (§18.4). The exact multiple is item 1.4's job, not fixed here. This is what gives "sustained density" (§22.4) its actual meaning: anything shorter-lived than one capacity-tick interval cannot trigger a transfer, without needing a magnitude threshold layered on top.

   Whether to act, once she looks, is a pure comparison — no tuned threshold. At each capacity-tick, Hera finds the single densest and single least-dense live VM. If they differ at all, a transfer is eligible. This is the same shape as §19.3's admission rule ("denser than the least dense resident") — a comparison of two intrinsic numbers, not a policy, so nothing needs inventing here.

   Both halves satisfy the tick-expressibility constraint item 1.3 states: the cadence is a tick multiple, and the decision itself reads only heat and mass, never wall time.

   What this does not resolve: how much capacity moves per eligible transfer. §22.3 only says the mechanism is "arithmetic on two integers"; neither this section nor item 1.3 pins down the amount. Reported rather than invented — it can become its own item if warranted, but is out of this item's scope.

3. The exact timescale ratio RESOLVED by item 1.4 — 1000:1. See §22.4.

4. Does the outer Stadium's own capacity ever change? RESOLVED by item 1.5 — no. §22 makes per-VM quotas elastic within a fixed total; the total itself is fixed for the machine's lifetime, set once at build via the Kconfig bound §20.5 #1 introduces. See §20.5 #1 for the full argument.

---

23. §12 Q1 dissolved, §12 Q2 sized

23.1 Q1 — the inline/by-reference threshold should not exist

Q1: Payload threshold — what size goes inline versus by reference.

§3's motivation is sound: a cell sized for a 1024-byte block would be grotesque for a patron that carries twelve bytes. But §19 supplies a better answer than a threshold.

If cells are small and uniform, a large patron occupies more of them, chained by index. That is exactly what mass already means. A block is not "by reference" — a block is heavy.

This closes the loophole recorded in §19.6 #1 without introducing a rule:

If the payload is in the Stadium, it counts toward mass. If it is not in the Stadium, the patron is not resident — it is a handle to the warehouse.

A 1 MB block cannot occupy one cell and read as dense, because its bytes are on the floor and the floor is what mass measures.

This is also what gives §19's hysteresis its teeth. Blocks should be expensive to keep resident — that is the entire reason migration back to Artemis is their reap event (§17.2). A threshold that let big patrons masquerade as light ones would have quietly disabled the mechanism.

Nothing in §3 is violated: cells stay fixed-size, links stay indices, the Stadium stays an array. Multi-cell patrons are consistent with all of it. By-reference is reserved for things genuinely outside the Stadium, and those are not patrons.

DECIDED — Q1 is dissolved rather than answered.

23.2 Q2's premise moved, and an unsettled question sits under it

Q2: Arena entry header size… The header must be sized for the worst case, and that case is the screen.

§17.5 removed the screen grid from the Stadium, so that premise no longer holds. What replaces it depends on something §17.5 established only halfway: it decided the dirty event is the patron, but not what one event covers.

Granularity	80×25 full redraw	Consequence
per cell	2,000 simultaneous patrons	floods the Stadium; starves every other patron
per line span / region	~25 patrons	negligible

A two-order-of-magnitude swing, currently undefined.

Recommend region-based. Framebuffer updates are naturally regional — a scroll dirties everything, a print dirties one span — overlapping regions coalesce for free, and per-cell events would make the console the numerically dominant patron kind in the entire system. That is absurd for something §17.5 correctly classified as a utility rather than an occupant.

LEANING region-based. It is a console-design decision as much as a Stadium one, so it should be confirmed when the console work happens rather than fixed here.

With that settled, the worst case for cardinality becomes messages — numerous, individually small. Which yields the sizing rule:

Size the cell so that a typical message is exactly one cell.

23.3 Concrete sizing — proposal, to be validated

These are numbers to check against a real build, not derived truths.

	Value	Reasoning
Cell size	64 bytes	one cache line; keeps density-ranking scans cache-friendly
Header — used	28 bytes	identity 8, heat 8, TTL 4, link 4, mass 2, flags + behaviour tag 2
Header — reserved	4 bytes	deliberate slack; see below
Header — total	32 bytes
Inline payload	32 bytes	a small message fits in one cell — mass 1
Per-VM Stadium	~4096 cells = 256 KB	hundreds of hot words and blocks, ACLs, messages in flight
Continuation cell	undetermined	see below — depends on an unsettled encoding

The four reserved bytes are deliberate rather than a rounding artefact. The fields above sum to 28; padding to 32 keeps the header a clean half-cell and gives the contains wire item 1.1 resolved to somewhere to live — a 4-byte index, the same width as link. (The header/continuation discriminator does not compete for this space: item 3.1 ruled it an external side bitmap, not a header field — see §3's amendment.) Whether 4 bytes is the final byte count item 3.1 settles on for contains, or whether it can shrink, is exactly the kind of thing item 3.1's real byte count settles, not this section — flagged here rather than assumed. Reserved space in a header that is expected to grow is cheaper than repacking one later.

256 KB per VM is comfortable against QEMU's -m 1024, and the outer Stadium's capacity (§20.5 #1) then follows from how many VMs the machine is willing to host.

The continuation cell — RESOLVED by item 1.12, linked

RESOLVED 2026-08-04. An earlier draft stated a 1024-byte block is "17 cells: 1 header + 16 payload." That figure assumed continuation cells are contiguous and carry nothing but bytes — an assumption this section settles rather than leaves open.

Linked, not contiguous — forced by what §22.3 already decided, not a fresh 50/50 choice. §22.3's per-VM free list (DECIDED) draws cells individually, with no adjacency guarantee. Guaranteeing contiguous runs for multi-cell patrons would mean changing that allocator to find runs rather than pop a free-list head, which reintroduces exactly the fragmentation §3 and §13 already ruled out by choosing fixed-size, index-linked cells in the first place. The allocator that exists says linked; contiguous would require an allocator that does not.

Consequence for sizing: each continuation cell carries a 4-byte next-index alongside its payload, leaving 60 bytes usable out of the 64-byte cell. A 1024-byte block needs 18 continuation cells at 60 usable bytes each, not 16 at a full 64 — the same figure this section's earlier draft flagged as the linked-form cost without yet choosing it. §23.3's sizing table is now complete on this row.

Firmness of each figure:

• Heat at 8 bytes is fixed, not chosen — Q48.16 in a uint64_t, matching execution_heat_q48 in the existing implementation.
• Link at 4 bytes caps the Stadium at ~4 billion cells, far past anything plausible. It could shrink to 3 or even 2 bytes if the header gets tight.
• TTL at 4 bytes gives ~4 billion ticks — over a year at 100 Hz. Almost certainly oversized; 2 bytes may do.
• Cell size 64 is the one to validate first, because everything else is expressed relative to it.

LEANING. The structure is decided; the constants are not.

23.4 Open

1. Dirty-event granularity (§23.2) — confirm region-based when console work begins.

2. Cell size validation. Build the header for real, count the bytes, and check that a typical message still fits in one cell with the behaviour tag and flags included.

3. Is identity needed at all for every patron kind? RESOLVED by item 1.10 (§25.2), 2026-08-04 — no, it cannot be elided. For a word it is a name; for a block a handle (§24.4); for a message possibly nothing — its identity could be its index. If identity can be elided for some kinds, 8 bytes of a 32-byte header is a large saving. This must not become a per-kind branch (§18.3), so it is only worth doing if it can be expressed uniformly.

   It cannot be, and the reason is a genuine conflict, not just difficulty. Two ways to elide it, both blocked:

   • Elide it only for kinds that don't need it (messages) while keeping it for kinds that do (words, blocks). This is exactly the per-kind branch §18.3 forbids — the engine, or something reading the header, would have to know a message's header is shaped differently than a word's, which reintroduces the type-field problem §3 exists to prevent.
   • Elide it everywhere, uniformly. This breaks the kinds that genuinely need it: a word is resolved by name, not by Stadium position — vm_dict_resolve_in_bucket() looks up by name — and a block is resolved by LBN, not by Stadium position either. The Stadium index is not a substitute for either; they are different addressing schemes serving different lookups.

   So the saving is not reachable without violating either §18.3's uniformity requirement or a lookup mechanism a patron kind already depends on outside the Stadium. identity stays a fixed, always-present 8-byte header field for every kind, whether or not a given kind's own logic makes use of it.

   Larger than it first appeared. §3 now declares cells a closed two-valued union — header or continuation. Whatever distinguishes the two occupies header space and interacts directly with any identity elision: a scheme that reuses the identity field as the discriminator, for instance, would couple the two decisions. Settle the header/continuation encoding first; identity elision is downstream of it. (Settled by item 1.12 — see §23.4 #4 — reinforcing that identity stays untouched by that encoding.)

4. The continuation-cell encoding. RESOLVED by item 1.12 — linked. See §23.3's "The continuation cell" subsection: forced by §22.3's already-decided disjoint free list, not a fresh choice. 4-byte next-index, 60 usable bytes per continuation cell, 18 continuation cells for a 1024-byte block. Item 3.1 is unblocked on this item.

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24. Mutation, identity, and mass stability

§17.4 #4 and §19.6 #2 ask whether patrons mutate in place. The question as posed does not survive contact with the patron kinds, and the version that does is cheaper.

24.1 Full immutability is not available

FORTH-79 blocks are mutable by definition: BLOCK returns a buffer, writes go into it, UPDATE marks it dirty, FLUSH writes it back. In a block editor that is a mutation per keystroke. A rule that every write produces a new patron would mean a new patron per keystroke.

Words already behave the opposite way. Redefinition creates a new dictionary entry rather than editing the existing one — which is why vm_dict_resolve_in_bucket() resolves in reverse-insertion order, newest visible definition winning.

The kinds genuinely disagree. Forcing them to agree would be §11's exception trap approached from the other side.

24.2 The concern was never payload — it was mass and identity

§19.6 #2 asks this for density stability: if mass changes underfoot, density changes and ranking is meaningless. §13 asks it because in-place mutation is what makes proofs expensive.

Neither concern is about payload bytes. A block's contents can change entirely and it is still 1024 bytes at the same handle.

So the invariant is narrower than immutability and costs almost nothing:

Tier	Rule
Identity	never changes for the life of the residency
Mass	never changes as a side effect of use
Header — heat, TTL, flags, link	mutates freely; this is the engine's work
Payload contents	may mutate in place, provided size and identity do not

DECIDED.

24.3 VMs appear to violate the mass rule, and do not

A VM's mass is elastic by §22 — that is the point of elasticity. But it changes only through Hera's arbitrated transfer, on the slow loop of §22.4. So the rule is not that mass is constant:

Mass changes only through an arbitrated transfer, never through traffic.

Traffic moves heat and nothing else. Density is therefore stable between transfers, which is what ranking requires, and §13 gets a mass function that changes at known, enumerable points rather than continuously.

24.4 A resident patron's identity is its handle, not its content hash

This follows from tier 1 and is worth stating because it is easy to get backwards.

A block's identity while resident is its handle — its LBN. Its content hash is computed at migration, for the warehouse. If identity were the content hash, editing a resident block would change its identity mid-residency and break tier 1 immediately.

§3 already permits this: identity is "handle or name". It never said hash.

Content-addressing therefore stays where it belongs — at the warehouse boundary, which is already how Artemis and the capsule model behave. The Stadium does not do content addressing; the warehouse does.

24.5 The rule this reduces to

No patron may grow or shrink while resident. If it needs to be a different size, it is a different patron.

No per-kind branching, no exception, and it holds for all five patron kinds.

24.6 Open

1. What happens to a resident block whose content changes, at migration time? RESOLVED by item 1.8 (§25.2), 2026-08-04. Its new content hash differs from the one it arrived with. The warehouse sees a new block; the Stadium saw one continuous residency. That is coherent, and the hand-off is: the new hash is computed exactly once, at the migration boundary, as part of the block's MIGRATE code field — consistent with §24.4 (a resident block's identity is its handle/LBN, never its content hash) and §17.2 (migration is the block's departure event, not destruction). Nothing about a resident block's identity changes mid-residency regardless of how many times its content mutates; the hash is a warehouse-side fact computed only when the block actually leaves.

   Whether the old hash is retained anywhere for audit is out of scope here. §5 draws this boundary already: the warehouse is beneath the Stadium, and the Stadium does not do content addressing — the warehouse does. Audit retention is an Artemis-layer policy question, not a Stadium one, and inventing an answer for it here would cross that boundary rather than respect it.

2. Does redefining a word while its old definition is resident leave two patrons? RESOLVED by item 1.9 (§25.2), 2026-08-04 — confirmed, yes. Not a design choice, a factual check: vm_dict_resolve_in_bucket() (dictionary_management.c:257) walks a bucket chain and returns the newest match — "the newest visible definition wins (FORTH-79 shadowing)" (:266). Nothing in the redefinition path unlinks or frees the superseded DictEntry; it stays in the bucket, merely shadowed. So if both the old and new definitions are hot, both are correctly on the floor, both have mass, both are ranked independently. This is the right behaviour, not an artefact to work around — they are genuinely two different words with two different execution histories.

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25. The punch list

This section is authoritative for what is done and what is not. Sections 1–24 are the design. This is the work.

---

25.0 How to implement this punch list

Read this subsection every time before touching an item. Do not skip it because it was read earlier in the session.

The rules

1. One item at a time. Take the lowest-numbered unchecked item whose prerequisites are met. Finish it completely. Do not begin a second item while one is in progress.

2. Do not jump ahead. Do not start a later item because it seems easy, related, or convenient. Do not do "while I'm in here" work. If a later item looks like it should be reordered, say so and wait for an answer — do not reorder unilaterally.

3. Do not increase scope. Do exactly what the item says. If the item says "write the trap entry," write the trap entry — not the trap entry plus a refactor of the file it lives in. Anything you notice that is not in the item gets reported, not fixed. This includes obvious bugs. Report them; they get their own item if they warrant one.

4. Do not fabricate, confabulate, or conflate. If you do not know how something works, read it. If you cannot determine it by reading, stop and say so. Never invent a function, a register name, a constant, a FORTH word, or an API that you have not verified exists in this tree or in the relevant hardware manual. Never guess at a value and present it as known. Never merge two things that are similar into one thing that is neither. A wrong answer stated confidently has cost this project git resets before.

5. When blocked, stop. Report exactly what is blocking, what was tried, and what is needed. Do not work around it silently. Do not substitute a different approach and carry on.

6. Acceptance is not optional and not negotiable. Each item states Done when. An item is not done until that exact condition is met and observed. Not "should work," not "compiles cleanly" unless that is what the item says. If acceptance requires the three-architecture QEMU boot, then all three have booted and their logs exist.

7. Report failures honestly. If a test fails, say it failed and show the output. If a step was skipped, say it was skipped and why. Never describe partial work as complete.

The commit discipline

Every checked-off item gets its own commit, and that commit contains:

• the code or document change for that item, and
• this file, with that item's checkbox changed from [ ] to [x].

Nothing else. One item, one commit. The punch list and the tree move together, so the document is never a claim about work that is not in the branch.

Commit message format:

<area>: <what the item did>            e.g.  riscv64: real trap entry with SRET return

Punch list §25 item <id> complete.
<one or two lines on what was actually verified, not what was intended>

Co-Authored-By: <the implementing model's attribution line, per its harness>

Standing constraints from .claude/CLAUDE.md

These override anything convenient:

• Never create a branch without explicit permission. Work on the branch you are on.
• Never stash. If the tree is dirty, report it and wait.
• Never apply a fix that was not requested. Report it instead.
• Acceptance for any kernel change is the three-architecture QEMU boot. There is no other test. The hosted make build is compile-sanity only.
• One QEMU instance at a time, foreground, clean before qemu. Concurrent runs corrupt the timing signal.
• Read experiments/bare_metal/README.md in full before editing any .4th file, and verify capsule edits with mkcapsule --lint rather than counting bytes by hand.

When an item is genuinely wrong

The design is not sacred. If implementing an item shows the design is wrong, stop, report what the code demonstrated, and propose the amendment. Amend the relevant section of this document first, get agreement, then continue. Do not implement something you believe is wrong because it is written down, and do not silently implement something different.

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25.1 Phase 0 — Substrate

Nothing in later phases can start until Phase 0 is complete. The engine has nothing to run on until there is a tick on all three architectures (§16.1, §16.5).

• 0.1 — Prune capsules/init.4th to Hera alone. Delete blocks 2051, 2052, 2053, 2054, 2055, 2056, 2058, 2059 — the readiness handshake, broadcast test, TRIPOD-TEST, HERMES-E2E, and fleet-DoE scaffolding. Edit the three surviving blocks: 2057 (BOOT-BANNER — drop the Tripod lines), 2049 (remove the Artemis and Hermes births with their CD-INIT calls and the common:msg.4th / process.4th loads; keep lib.4th; adjust VM-TREE / VM-CHILDREN), and 2050 (keep the BOOT-BANNER call; remove the READINESS-HANDSHAKE and BROADCAST-TEST calls). Leave capsules/hermes/ and capsules/artemis/ untouched on disk. An earlier draft of this item said "remove blocks 2050–2059," which contradicted its own Refs line — 2050 survives, edited (C1). Done when: all three architectures boot to the prompt with Hera alone, no Hermes or Artemis in the banner, and the three logs exist under logs/. Refs: the surviving blocks are 2057, 2049, 2050. mkcapsule --lint before building.

• 0.2 — riscv64: real trap entry. Replace the one-way riscv64_trap_entry in arch/riscv64/isr.S with save / dispatch / restore / sret. Route scause bit 63 + cause 5 to the timer path; everything else keeps falling through to the existing fatal handler. FP state is not optional (B2 verified): the kernel builds -march=rv64gc -mabi=lp64d (Makefile.starkernel:162) — hard-float ABI, and kernel code genuinely uses doubles (hotwords_stats_print). The trap entry must save the ABI's caller-saved FP registers plus fcsr alongside the integer set; verify the exact register list against the RISC-V psABI, not this document. Do not "fix" this by switching to soft-float — that breaks existing code and is a build-system decision nobody has made. Done when: riscv64 boots to the prompt with no regression, and exceptions still halt with the same diagnostic as before. No trap source exists yet at this item — the timer arms in 0.3, whose tick-advance acceptance is what proves this entry path took and returned an interrupt (C2). Do not arm the timer early to manufacture evidence here.

• 0.3 — riscv64: SBI timer and real time base. First, the prerequisite this item silently assumed (B1 verified it absent): the kernel has no DTB access — BootInfo (uefi.h:624-639) carries no FDT pointer and no FDT code exists in the tree. Capture the DTB pointer from the EFI configuration table (DTB table GUID) into a new BootInfo field in the shared loader. This also serves 0.6. Then: arm the timer via the SBI TIME extension, enable sie.STIE, and re-arm inside the handler on every tick — the SBI timer is one-shot by nature, and a missed re-arm stops the heartbeat forever with no error. That is the single most likely silent failure of this item (C3). Switch the time base from rdcycle to the time CSR and take its frequency from the device tree timebase-frequency, with a named fallback constant — not a bare magic number (§16.2). Done when: heartbeat_ticks() advances on riscv64 and the tick interval matches the configured rate within measurement noise. Verify the SBI extension is present before relying on it; if it is absent, stop and report rather than falling back silently.

• 0.4 — aarch64: determine the exception level at runtime. Read CurrentEL once, early, and let it govern everything EL-dependent, not just the timer (B3): the vector base register (VBAR_EL1 vs VBAR_EL2 — today's isr.S writes VBAR_EL1 unconditionally, which is never consulted for exceptions taken at EL2), the saved-state pair (ELR_ELx/SPSR_ELx), and the timer register set (CNTP_*_EL0 vs CNTHP_*_EL2). Do not hardcode either level anywhere. Done when: the boot log states which EL was detected, on real QEMU output.

• 0.5 — aarch64: IRQ vector split. Split irq_spx out of the shared fatal handler in arch/aarch64/isr.S: save x0–x30 plus the saved-state registers (see B3 note below), call a C handler, restore, eret. The other fifteen vectors are unchanged. Note the 128-byte slot limit — the save sequence will not fit inline and must branch to a trampoline. FP state is not optional (B2 verified): the kernel builds without -mgeneral-regs-only (Makefile.starkernel:146), so the compiler may use SIMD registers anywhere. Save the ABI's caller-saved SIMD set plus FPSR/FPCR alongside the integer set; verify the exact list against the AAPCS64, not this document. EL governs the whole path (B3): this item previously hardcoded ELR_EL1/SPSR_EL1, while 0.4 refuses to hardcode the EL — and today's isr.S installs VBAR_EL1, which is never consulted for exceptions taken at EL2. The EL detected in 0.4 must select the vector base register (VBAR_ELx), the saved-state pair (ELR_ELx/SPSR_ELx), and the eret target state, not just the timer registers. Done when: aarch64 boots to the prompt with no regression. No IRQ source exists yet at this item — the GIC lands in 0.6 and the timer arms in 0.7, whose tick-advance acceptance is what proves this path took and returned an IRQ (C2). Do not pull 0.6/0.7 work forward to manufacture evidence here.

• 0.6 — aarch64: minimal GICv2. Enable the distributor and CPU interface, set the priority mask, enable the timer PPI, acknowledge via IAR / EOIR. Read the base addresses and the PPI INTID from the device tree — do not take them from memory or from this document. The DTB pointer comes from the BootInfo field added in 0.3 (B1 verified no such field existed). If the DTB turns out to be unreachable on aarch64 EDK2, stop and report — deciding between loader work and named QEMU-virt constants with a recorded caveat is Captain Bob's call, not the implementer's.

  DTB confirmed unreachable (checked live, 2026-08-03) — same finding as riscv64. fdt_valid(boot_info->dtb) fails on this system's aarch64 build too (installed firmware: qemu-efi-aarch64 2025.11-3ubuntu7, no alternate available). Ruling: named QEMU-virt constants, verified rather than recalled — qemu-system-aarch64 -machine virt,dumpdtb=... was used to dump QEMU's own internal devicetree (the one EDK2 fails to forward) and decoded with this tree's own fdt.c reader, giving GICD 0x08000000, GICC 0x08010000 (both confirmed for this exact QEMU 10.2.1 build, not assumed stable across versions) and PPI 30 for the non-secure EL1 physical timer (bonus finding: PPI 26 for the EL2 hypervisor timer, for item 0.7's EL2 path). Register offsets (GICD_CTLR, GICC_IAR, etc.) are architectural, not board-specific, and were cross-checked against /usr/src/linux-headers-*/include/linux/irqchip/arm-gic.h rather than recalled.

  Acceptance corrected — same defect C2 already fixed for items 0.2 and 0.5, missed here. "The timer interrupt is delivered and acknowledged" cannot be observed within this item's own scope: nothing arms the timer until item 0.7's apic_timer_start(). As written this item could never be marked done on its own evidence. Acceptance is now the same shape as 0.2/0.5: GIC initialises without fault, IAR/EOIR path is wired into aarch64_irq_handler() and ready, boots with no regression. Item 0.7's tick-advance acceptance is what proves this path actually delivers and acknowledges an interrupt, exactly as 0.5 already defers to 0.7 for the same reason.

  Done when: GIC distributor and CPU interface initialise without fault; the timer PPI is enabled; aarch64_irq_handler() reads IAR, dispatches, and writes EOIR; boots to the prompt with no regression. Scope is one interrupt; a general GIC driver is out of scope and must not be written.

• 0.7 — aarch64: arm the generic timer. apic_timer_start() / apic_timer_stop() using the register set chosen in 0.4, re-armed each tick. Done when: heartbeat_ticks() advances on aarch64 at the configured rate.

• 0.8 — Converge the three architectures on one tick path, and make the physical heartbeat adaptive. One heartbeat_tick() call site per architecture; the ISR does counter, timestamp and flag only. Per the GAP-A1 ruling, the hardware tick drives instrumentation only: the bottom half services TIME-TRUST bookkeeping, and the engine (vm_tick(), decay, inference) stays on the virtual tick — execution-paced, exactly as today. Nothing that feeds patron state reads the hardware counter.

  Per §26 (ruled): the physical re-arm period is no longer a fixed 100 Hz constant. heartbeat.c owns the current adaptive period (heartbeat_set_adaptive_period_ns() / heartbeat_next_period_ns()); Loop #7's existing site in vm_runtime.c calls the setter with its stable/volatile-derived value, rescaled to the 10 ms kernel base per §26.3 (not the 10 µs hosted HEARTBEAT_TICK_NS); each architecture's re-arm function reads the getter and converts to its own raw counter units instead of using a hardcoded period. No new concurrency primitive — single writer (mainline), single reader (ISR), same shape §21.1 already found free on one hart. Done when: all three architectures drive the same TIME-TRUST bottom half; no loop math runs in interrupt context; vm_tick()'s call sites are unchanged.

  Live variation not directly observed. The wiring (heartbeat_set_adaptive_period_ns() → heartbeat_next_period_ns() → each architecture's re-arm function) was verified by code inspection and successful three-architecture build/link, and boot regression is clean (identical parity dict hash on all three, pre- and post-change). But a temporary diagnostic confirmed Loop #7 itself never fired during a live QEMU session — a synthetic SPIN loop drove ~6,500 word executions (past HEARTBEAT_INFERENCE_FREQUENCY's 1000-tick threshold) without tripping vm_tick_inference_engine()'s pre-existing !vm->rolling_window.is_warm gate (vm_runtime.c:583). That gate predates this item and was not investigated further — out of scope. So: the mechanism is real and correctly connected: whether it actually moves the hardware re-arm period under real load is unconfirmed, pending either a fuller DoE run in a later phase or a dedicated look at the warm-up gate. Refs: §16.4 (as ruled), §18.4, §21.2, §26.

• 0.9 — Write the concurrency constraint at the mutex stub. Add a comment at src/starkernel/vm/host/shim.c:415 stating that the no-op is correct only while nothing in interrupt context mutates shared structure, and that making it a real spinlock would deadlock a single hart. Done when: the comment is in place. This is a documentation item; no behaviour changes. Refs: §21.2, §21.5 #1.

• 0.10 — Phase 0 acceptance. Full three-architecture QEMU run. Confirm: boots to prompt on all three; tick count non-zero on all three; on riscv64 after 0.3, trust near Q48_ONE and variance small relative to the new expected_delta — not merely "sane", which is unfalsifiable (C6); amd64 output unchanged from its pre-branch behaviour (a valid control under the GAP-A1 ruling, since 0.8 no longer touches engine plumbing). Then boot one architecture twice and confirm the parity dict hash is identical across runs. If it drifts, something is firing on wall time and Phase 0 is not complete. Done when: all of the above observed, logs committed.

  Observed 2026-08-04. All three boot to ok>. Tick count at the point just before sk_repl() (a bounded wait for 3 real ticks was added at kernel_main.c — with none, the count landed on 1 (amd64) and 0 (riscv64) purely from how little wall time elapses between arming the timer and this print, which is not the same claim as "the heartbeat doesn't tick" and would have been a false negative to report as one): amd64 4, riscv64 3, aarch64 3. riscv64: trust=0x00010000 (exactly Q48_ONE), variance=0x0. amd64: dict_hash=0x3d4e1daf289da94f, identical to the pre-item-0.8 baseline (logs/20260803-231322) — unchanged output, as the GAP-A1 control requires. Two consecutive amd64 boots (logs/20260804-001948, logs/20260804-002021) both produced dict_hash=0x3d4e1daf289da94f — reproducible, no wall-clock leakage into patron state. Logs committed: logs/20260804-001727 (amd64), logs/20260804-001805 (riscv64), logs/20260804-001850 (aarch64), logs/20260804-001948 / logs/20260804-002021 (amd64 double-boot pair). Refs: §16.4, §18.5.

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25.2 Phase 1 — Design questions to settle on paper

These need answers, not code. Each one is settled by amending the relevant section of this document and committing that amendment as its own item.

• 1.1 — Exclusive access ("sitting in a car"). §8 asserts a per-patron exclusivity primitive that is not a global lock. Nothing defines it. Decide what it is, what it blocks, and what happens if a patron is selected for reaping while held. Refs: §8. This is the largest unresolved design question.

  Hard prerequisite of item 3.1, and its outcome may amend §3. This item is filed in Phase 1 alongside questions that have no structural effect, and it is not in that class. A per-patron exclusivity primitive plausibly needs a held flag or a holder index — a ninth wire in §3's table, in the header item 3.1 builds. Resolve 1.1 after 3.1 and the cell header gets rebuilt.

  §25.4 already blocks Phase 3 on items 1.1–1.7, so the ordering is right. What was missing is why 1.1 specifically — which is the kind of omission that gets an item quietly reordered later by someone who does not know what it was holding up. §23.3 reserves 4 header bytes partly against this outcome.

  RESOLVED 2026-08-04 — containment, not a lock. A ninth wire, contains (§3): an index to the patron currently held inside this one, or none. Reap is gated, not density-derived — a patron with a non-none contains link cannot be reaped, full stop. Chains up to a depth cap, default 5, exposed as a Kconfig symbol (named at implementation time in item 3.1) rather than hardcoded — this project's existing tunable-knob convention. Unwinding is innermost-first, forced by the chain's own topology, not a policy choice — no FIFO/LIFO decision exists to make. Single occupant per level. Full argument in §8. Same-Stadium relationship — distinct from item 1.7's VM-tree-recursion question (§20.5 #4), which this does not resolve and remains open. Item 3.1 is now unblocked on this item; the ninth wire and the reserved header bytes (§23.3) are the concrete carry-forward.

• 1.2 — The resting floor. Whether a VM's quota has a floor, and whether it is the mass of its pinned patrons (derived) or a constant (tuned). Refs: §22.5 #1.

  RESOLVED 2026-08-04. Floor = max(mass of pinned patrons, one message-sized cell). Both terms derived, neither tuned — the second closes a reachability gap the first term leaves open for a VM with nothing pinned (zero quota means it can never receive the message that would let it regrow). Full argument in §22.5 #1.

• 1.3 — What triggers a capacity transfer. Hera arbitrates; on what signal, and how often. Should read the density gradient, not a schedule. Constraint, not optional: arbitration mutates patron mass, so §18.5's invariant binds it directly — anything that influences patron state advances on tick count; wall-clock time may be recorded for diagnostics and must never be an input to a decision. Pacing arbitration off a wall-clock interval would reintroduce exactly the defect item 2.1 exists to remove, in a new place. Whatever 1.3 decides must be expressible in ticks. Refs: §22.5 #2, §18.5, §22.4.

  RESOLVED 2026-08-04. Hera evaluates once per capacity-tick (a coarser, derived multiple of the virtual tick — the multiple itself is item 1.4). At each capacity-tick she finds the single densest and single least-dense live VM; if they differ at all, a transfer is eligible — a pure comparison, no tuned threshold, same shape as §19.3's admission rule. Cadence carries the "sustained density" requirement; the decision itself is a comparison. Both are tick-expressible, never wall-clock. Not resolved: how much capacity moves per transfer — reported, not invented, out of this item's scope. Full argument in §22.5 #2.

• 1.4 — The heat/capacity timescale ratio. The ordering is fixed (capacity slower); the ratio is not. Refs: §22.4, §22.5 #3.

  RESOLVED 2026-08-04 — 1000:1. The capacity-tick gets its own named constant, defaulted to 1000 virtual ticks, matching the existing precedent at capsule_vm_physics.c:434-441 (vm_physics_heartbeat_tick()'s HEARTBEAT_INFERENCE_FREQUENCY-gated fleet recalibration loop) rather than an invented number. Comfortably past §12 Q5's order-of-magnitude minimum. Kconfig-tunable at implementation (item 3.1). Full argument in §22.4.

• 1.5 — The outer bound. The outer Stadium's capacity, and the behaviour at the bound: birth refused, or coldest VM reaped. Refs: §20.5 #1, §22.5 #4.

  RESOLVED 2026-08-04. Bound = 4 (matches Tripod's known topology: Hera + 2 Hermes + Artemis), Kconfig-tunable, explicitly a placeholder pending a later DoE campaign to find an idealized default rather than a second guess made on paper. Fixed for the machine's lifetime once set at build. At the bound, birth is refused — not coldest-VM-reaped, which the original text called "consistent with §19.3" but which does not survive §20.2's cold-start birth rule (a newborn can never out-density an existing warm VM). Making room stays Hera's own deliberate act. Full argument in §20.5 #1.

• 1.6 — A VM's mass: allocated share, or one cell. Refs: §20.4, §20.5 #2.

  RESOLVED 2026-08-04 — allocated share. Less a fresh choice than a confirmation of what §22's elasticity mechanism and §24.3 already treated as decided, and what items 1.2–1.5 already assumed. The one-cell alternative would make outer-level density collapse to heat alone, discarding the starved-vs-small diagnostic that's the entire point of §20.4. Full argument in §20.4.

• 1.7 — Rule out recursion beyond two levels — deliberately, not by omission. Refs: §20.5 #4.

  RESOLVED 2026-08-04 — Kconfig-tunable cap, default 2. Not a hard prohibition: bounded, same treatment as item 1.1's containment depth. 2 matches §21's already-decided two-level structure (outer VM Stadium, per-VM inner Stadium). Enforced explicitly at VM-birth time — a birth that would exceed the configured depth is refused. Full argument in §20.5 #4.

• 1.8 — Block content change at migration. A resident block whose content changed has a different hash on the way out. State the hand-off. Refs: §24.6 #1.

  RESOLVED 2026-08-04. New hash computed exactly once, at the migration boundary, as part of the block's MIGRATE code field — the resident identity (handle/LBN) never changes mid-residency. Whether the old hash is retained for audit is an Artemis-layer question, out of scope for the Stadium per §5's boundary. Full argument in §24.6 #1.

• 1.9 — Redefined words as two resident patrons. Confirm both may be on the floor. Refs: §24.6 #2.

  RESOLVED 2026-08-04 — confirmed, yes. Factual, not a design choice: vm_dict_resolve_in_bucket() keeps both entries resident with newest-wins shadowing, no GC on redefinition. Correct behaviour, not an artefact. Full argument in §24.6 #2.

• 1.10 — Identity elision. Whether identity can be dropped for some kinds without a per-kind branch. Optimisation; may be closed as "no". Refs: §23.4 #3.

  RESOLVED 2026-08-04 — closed as no. Eliding it per-kind reintroduces the type-field branch §18.3 forbids; eliding it uniformly breaks lookups words and blocks already depend on outside the Stadium (name, LBN). Neither path is reachable without violating an existing constraint. identity stays a fixed, always-present 8-byte field for every kind. Full argument in §23.4 #3.

• 1.11 — Dirty-event granularity. Leaning region-based. Blocked on item 4.3 — it is settled as part of the console migration, not speculatively before it (C5). Refs: §17.5, §23.2, §23.4 #1.

• 1.12 — The continuation-cell encoding. Contiguous (continuation cells are pure payload; allocation must find runs, reintroducing fragmentation) or linked (each continuation cell carries a next-index, costing 4 bytes of payload and changing every large patron's mass). §22.3's per-VM free list guarantees no adjacency, so linked is the default unless allocation changes. This was §23.4 #4 — a stated blocker of item 3.1 that was never a schedulable item until now (C4). Settling it completes §23.3's sizing table. Refs: §23.4 #4, §23.3, §22.3. Prerequisite of 3.1.

  RESOLVED 2026-08-04 — linked. Forced, not chosen: §22.3's disjoint per-VM free list gives no adjacency guarantee, and guaranteeing contiguity would reintroduce the fragmentation §3/§13 already ruled out. 4-byte next-index, 60 usable bytes per continuation cell, 18 continuation cells for a 1024-byte block. §23.3's sizing table is complete; item 3.1 is unblocked on this item. Full argument in §23.3's "The continuation cell" subsection.

---

25.3 Phase 2 — Prepare the existing physics

• 2.1 — Restate heat transfer on the virtual tick. vm_physics_touch() scales transfers by wall-clock elapsed time (capsule_vm_physics.c:272). Restate it on the virtual tick — the execution-derived counter of §16.4 as ruled, not the hardware heartbeat, whose interleaving with execution is wall-clock-dependent and would leave the acceptance below unachievable (§25.7.1 GAP-A1). Done when: no wall-clock value influences heat, and the same capsule booted twice produces an identical fleet heat sum across the two runs — achievable now that both the touch points and the elapsed-tick values are deterministic functions of execution. Refs: §16.4 (as ruled), §18.5, §19.6 #3.

  Acceptance corrected. This item previously accepted on the dictionary-hash double-boot check from 0.10. That cannot detect this work: §18.5 establishes that vm_physics_touch() writes node->physics, not DictEntry.execution_heat, and therefore never reaches the parity hash. The dict hash would be identical whether 2.1 succeeded, failed, or was skipped. Fleet heat is the quantity this item changes, so fleet heat is what has to be compared. Run 0.10's dict-hash check as well, as a regression guard — but it is not evidence for 2.1.

  DONE 2026-08-04. vm_physics_touch() no longer takes a now_ns parameter at all — it reads fleet_heartbeat_tick_count internally, which vm_runtime.c:143 confirms is execution-paced (advanced once per vm_tick() call), not wall-clock. VMPhysics.last_active_ns → last_active_tick; VMFleetTouchSample.elapsed_us → elapsed_ticks; a new explicit touched flag replaces the old > 0 sentinel, which doesn't safely carry over to tick counts (a genuine first touch can land on tick 0). The three call sites (VM-EXEC, VM-CALL, VM-STEP in mama_forth_words.c) dropped vm_monotonic_ns(vm) accordingly. vm_physics_heartbeat_tick()/vm_physics_tick()'s own dead now_ns parameters were left alone — already unused, already documented as such, out of this item's scope.

  Regression: clean. All three architectures boot to ok> with identical dict_hash=0x3d4e1daf289da94f, matching the item-0.10 baseline, on amd64 (×2), aarch64, and riscv64. Logs: logs/20260804-113146, logs/20260804-113233 (amd64 pair), logs/20260804-131020 (aarch64), logs/20260804-131119 (riscv64). No new compiler warnings in the touched files.

  Honest limitation on the fleet-heat-sum acceptance criterion. With Tripod pruned to Hera alone (item 0.1), vm_physics_touch()'s fan-out has no other live VM to pull heat from — others_total is always 0, so the fleet heat sum is trivially Q48_ONE on every boot regardless of whether the tick logic is correct. The double-boot dict-hash match is a valid regression guard (as the acceptance note above already says), but it does not actually stress-test this item's new code path. A real check needs at least one other live VM to touch, which returns in Phase 4 (Hermes/Artemis) — not fabricated here.

  Unresolved, flagged not fixed: fleet_transfer_slope_q48's seed (65536/3) was calibrated against elapsed wall-clock microseconds; elapsed ticks between touches is a different quantity at a different scale, and the seed has not been re-fit against it. Left as-is per §25.0 rule 4 (no invented numbers) — a real re-tune is DoE work (item 5.1), and can only be meaningfully measured once Phase 4 restores a multi-VM fleet anyway, per the limitation just above.

• 2.2 — Bound the VM registry. The registry is a kmalloc-backed unbounded list (capsule_vm_physics.c:71-72). Give it the hard bound decided in 1.5. Done when: the population is bounded, birth at the bound behaves as 1.5 specifies, and the three-architecture boot is unaffected. Refs: §2, §13, §19.2, §20.2.

  Justification corrected. This item previously read that the registry "makes fleet K an identity that cannot fail" and accepted on VM-CONSERVED? becoming able to fail. Both were wrong, and the reason is now in §20.2: heat is transferred, not renormalised, so conservation is already a real invariant and already falsifiable — by the dropped-remainder path at :240-244 and by integer truncation at :304-305. Bounding the population changes neither.

  The bound is still needed, on the two grounds §2 now states: finite state for §13's induction and model checking, and density requires a capacity to be dense within (§19.2), without which §19.3's admission rule has nothing to compare against. Those are the honest justifications and this item now rests on them.

  Making conservation more falsifiable is a different and larger piece of work — fixing the truncation leak — and is recorded in §25.7 rather than folded in here.

  DONE 2026-08-04. STADIUM_MAX_VM_COUNT Kconfig symbol (default 4, per item 1.5), wired through Makefile.starkernel and given the missing starforth_config.h fallback default (STARFORTH_CONFIG_STADIUM_MAX_VM_COUNT_DEFAULT) that the earlier WIP commit omitted — without it the macro was only ever defined when a Kconfig .config was active, and this build has none, so the first compile attempt failed with STADIUM_MAX_VM_COUNT undeclared. vm_registry_live_count() (added in the prior WIP commit, counts only VM_STATE_LIVE nodes) is now called in capsule_birth_baby() (src/starkernel/capsule/capsule_birth.c), between capsule validation and vm_registry_alloc(), so a full fleet is refused — returning the new CAPSULE_RUN_ERR_FLEET_FULL and logging via capsule_parity_log_birth_failed() with vm_id=0 (no VM is allocated on this path) — before any EMBRYO registry slot is consumed.

  Regression: clean. All three architectures boot to ok> with identical dict_hash=0x3d4e1daf289da94f, matching the item-0.10/2.1 baseline: amd64 (logs/20260804-134914), aarch64 (logs/20260804-134957), riscv64 (logs/20260804-135102).

  Honest limitation. With Tripod pruned to Hera alone (item 0.1), the fleet never reaches STADIUM_MAX_VM_COUNT during boot, so this run exercises the bound-check code path only in the trivially-not-full case — the actual refusal branch is unexercised until Phase 4 restores a multi-VM fleet. Same caveat item 2.1 already recorded for the same reason.

---

25.4 Phase 3 — Stadium core

Blocked on Phase 0 complete, and on items 1.1–1.7 and 1.12.

• 3.1 — Cell and header. Define the entry with all eight wires (§3) — nine if item 1.1 resolves to a holder index. Define both members of §3's closed two-valued union: patron header and continuation cell. Validate the 64-byte cell by counting real bytes; adjust and record if it does not fit. Blocked on: item 1.1 (may add a wire) and item 1.12 (the continuation-cell encoding — contiguous or linked — which sets the mass of every large patron and cannot be guessed). Refs: §3, §23.3, §23.4 #4.

  DONE 2026-08-04. StadiumPatronHeader and StadiumContinuationCell defined in the new include/starkernel/vm/stadium.h, unioned as StadiumCell; translation unit src/starkernel/vm/stadium.c added to Makefile.starkernel's LOADER_EXTRA_SRCS / KERNEL_EXTRA_SRCS so the header actually gets compiled, not merely included by something that never builds.

  Discriminator ruling, made before this item's code was written (Captain Bob's call): the header/continuation discriminator is an external side bitmap, one bit per cell, kept outside the 64-byte cell array — not a header field. Amended into §3 and §23.3 accordingly. Item 3.1 declares the bitmap's purpose and indexing contract in a comment; it does not allocate it — that is item 3.2's scope, since sizing depends on the memory budget item 3.2 works from.

  Byte count, both counted for real, both exactly 64 with zero compiler-inserted padding (verified via three C99-portable negative-array-size assertions, no _Static_assert — this project targets C99, not C11):

  • StadiumPatronHeader: identity u64(8) + heat u64(8) + ttl u32(4) + link u32(4)
    • contains u32(4) + mass u16(2) + flags u8(1) + behaviour u8(1) + payload u8[32] = 64. pin lives as bit 0 of flags, not its own field, matching §3/§23.3. Fields ordered largest-to-smallest so every offset is already a multiple of its own alignment and the 64-byte total is a multiple of the struct's 8-byte max alignment — no padding, without resorting to a packed attribute (a GNU extension, forbidden by CLAUDE.md's strict-ANSI-C99 rule). Because the discriminator moved outside the cell, this matches §23.3's original 32-byte-header / 32-byte-inline-payload proposal exactly — no adjustment needed here, unlike the continuation cell below.
  • StadiumContinuationCell: next u32(4) + payload u8[60] = 64, unchanged from item 1.12's figure — the discriminator living outside the cell means neither variant's byte budget was disturbed by it.

  Assertion proven live, not just present: temporarily changed the header check's expected size to 63, recompiled stadium.c standalone (cc -std=c99 -Wall -Werror -Wextra -D__STARKERNEL__), confirmed the build failed with error: size of array 'stadium_header_size_check' is negative, then restored it and confirmed a clean compile.

  Regression: clean, and stadium.o confirmed present. All three architectures boot to ok> with identical dict_hash=0x3d4e1daf289da94f, matching the item-2.2 baseline — amd64 (logs/20260804-145132), aarch64 (logs/20260804-145232), riscv64 (logs/20260804-145329). find build/<arch> -iname stadium* confirmed obj/loader/vm/stadium.o and obj/kernel/vm/stadium.o both exist post-build, closing the gap the WIP on item 2.2 exposed: a header nothing compiles proves nothing.

  Open, deferred honestly: §23.4 #2 ("does a typical message still fit in one cell") remains unanswered — there is no message patron struct anywhere in this tree yet (messages are undesigned future work), so there is nothing concrete to check the 32-byte inline payload against. Not fabricated a number to close this; left open.

  REOPENED 2026-08-04. While reading context for item 3.2, found that two earlier resolutions had explicitly named this item as where their Kconfig symbols would be implemented — item 1.1 (line ~2400, "exposed as a Kconfig symbol, named at implementation time in item 3.1", the contains-chain depth cap, default 5) and item 1.4 (§22.4 and its own resolution, "Kconfig-tunable at implementation (item 3.1)", the capacity-tick constant, default 1000). Neither made it into the work above, because 3.1's own stated scope ("cell and header") never mentioned them — the promise lived only in items 1.1 and 1.4's text. Captain Bob ruled: reopen, add both here (Phase 3 is implementation, unlike Phase 1's paper-only items — item 1.7's own nesting-depth Kconfig symbol was correctly left undone at Phase 1, by contrast). Declaration only, matching how STADIUM_MAX_VM_COUNT was introduced in item 2.2's WIP commit before its consuming logic existed: STADIUM_CONTAINS_DEPTH_MAX (default 5) has no consumer yet — reap-gating on contains is item 3.5's scope. STADIUM_CAPACITY_TICK (default 1000) has no consumer yet either — capacity arbitration isn't on the punch list at all yet. Not inventing that logic here; only the two symbols.

  RE-CLOSED 2026-08-04. Both symbols added following STADIUM_MAX_VM_COUNT's exact pattern: Kconfig.kernel entry, Makefile.starkernel kconfig_int + VM_FEATURE_FLAG_VARS forwarding, starforth_config.h fallback default (needed for this no-.config build, same gap the original STADIUM_MAX_VM_COUNT WIP commit hit and item 2.2 fixed). stadium.h now includes starforth_config.h and carries two more C99-portable compile-time checks (> 0, not byte-count) proving both symbols are defined and sane in the same translation unit as the cell checks. contains's field comment now references STADIUM_CONTAINS_DEPTH_MAX by name. Recompiled stadium.c standalone (clean) before the full run.

  Regression: clean, re-run after reopening. All three architectures boot to ok> with identical dict_hash=0x3d4e1daf289da94f -- amd64 (logs/20260804-151032), aarch64 (logs/20260804-151115), riscv64 (logs/20260804-151222).

• 3.2 — Boot-time allocation. One global cell array, sized from the memory budget, before any VM exists. Refs: §6, §17.6, §22.3.

• 3.3 — Behaviour enumeration and dispatch. Closed tag set fixed at build time. Enumerate behaviours, never patron kinds. Refs: §13, §18.3.

• 3.4 — Density ranking. Heat ÷ mass, read not computed. Refs: §19.2, §19.3.

• 3.5 — Admission and eviction. Admit if denser than the least dense resident. Refs: §19.3.

• 3.6 — Hera as patron zero, pinned. Assert at the eviction site; selecting Hera is a panic, not a filtered candidate. Refs: §20.5 #3.

---

25.5 Phase 4 — Migrate the subsystems

One subsystem at a time, converted completely. Never two live heat mechanisms at once (§11).

• 4.1 — Hot words onto the Stadium. Replaces the round-robin eviction with density ranking. Measurable before and after via stats.evictions / stats.promotions. Refs: §17.3.
• 4.2 — Hermes native on the Stadium. The proving ground; produces the effort number. Refs: §10.
• 4.3 — Console. Settles 1.11 as part of the work. Refs: §17.5.
• 4.4 — Artemis last. It works today; it is the thing that cannot be broken. Refs: §10.

---

25.6 Phase 5 — Verification and measurement

• 5.1 — Re-run the DoE on the new substrate. A green POST suite is not evidence that K holds; those are different claims. Refs: §10.
• 5.2 — Isabelle/HOL. One datatype, one index space, one conservation theorem. Refs: §13, §22.3.
• 5.3 — Shrink the subsystem documents. ARTEMIS.md, HERMES.md, CONSOLE.md, TRIPOD.md should each reduce to roughly three lines. Any that grows is fighting the design. TRIPOD.md also needs its Immediate Goal rewritten — it currently requires Hera to spawn Hermes and Artemis at boot, which 0.1 undoes. Refs: §11.

---

25.7 Reported, not scheduled

Found while reading. Not fixed, not assigned. They become items only if Captain Bob says so.

• Fleet heat leaks on every multi-VM touch. vm_physics_touch() fans out (moved_total * heat) / others_total per VM in integer arithmetic (capsule_vm_physics.c:304-305); the shares sum to less than moved_total, so total fleet heat drifts downward monotonically. VM_PHYSICS_EPSILON_Q48 is 5% of Q48_ONE, so a long enough run would trip VM-CONSERVED?. Nobody has measured the rate. This is a live defect in a conservation law the project makes claims about — see §20.2.

  Note to self, flagged by Captain Bob 2026-08-04, before item 5.1. Currently invisible: with Tripod pruned to Hera alone (item 0.1), others_total is always 0, so this path is never exercised — nothing today can trip it. It becomes reachable, and therefore measurable, the moment Phase 4 restores Hermes/Artemis. Check this before trusting item 5.1's DoE re-run as evidence that VM-CONSERVED? holds: a clean run on a document this careful about falsifiability elsewhere, sitting on top of an unmeasured, monotonic leak, would be a false negative, not a green light. Still reported-not- scheduled on purpose — becomes its own item only if Captain Bob says so.

• hotwords_cache_promote() writes NULL into the ring if word is NULL and the cache is full (physics_hotwords_cache.c:363-364). Unreachable today.

• heartbeat_trust() is exported and has zero callers.

• m5_time_trust and m5_variance (include/vm.h:315-316) are declared and never used.

• src/*.c.bak files are tracked in git at the src/ top level.

• The bump-z / bump-y targets in the hosted Makefile reference version macros that do not exist in the generated include/version.h.

• Taxonomy and lexicon. Raised by Captain Bob 2026-08-04, mid-item-3.1. This document's physics-flavored vocabulary (heat, mass, density, patron, Stadium, and the rest) needs a glossary that is explicit these are named analogies, not physical claims — and that also covers the growing set of Kconfig build knobs (STADIUM_MAX_VM_COUNT and its siblings) so the terminology in code, Kconfig help text, and this document stays one language instead of drifting apart. Not scoped, not placed in a phase. Captain Bob: "I guess that we didn't finish out FABRIC.md quite as much as we thought."

25.7.1 Second review pass — 2026-08-03, pre-coding. Awaiting rulings.

A full re-read of this document as it stood after the first review's corrections, looking for what would break a lower-capability model working the punch list.

Status: all fourteen findings closed, 2026-08-03. A1 ruled (virtual tick) and applied to §16.4/§17.1/§18.4 and items 0.8/2.1. B1 verified (no DTB access; fixed into 0.3/0.6), B2 verified (no FP restriction on any arch; fixed into 0.2/0.5), B3 applied (EL governs the vector path; 0.4/0.5). C1–C7 applied to their items; D1–D3 swept. The findings below are preserved as the record of what was found and why.

GAP-A1 — §16.4's central inference is unsound. NEEDS RULING RULED 2026-08-03: virtual tick.

Applied. The recommended resolution below was adopted by Captain Bob. §16.4, §17.1 and §18.4 now carry the ruling; items 0.8 and 2.1 were reworded to it. Item 0.10 needed no change: with the engine staying execution-paced, its double-boot dict-hash check is a valid regression guard and the amd64-as-control framing is accurate again, since 0.8 no longer touches engine plumbing on any architecture. The argument below is preserved as the record of why.

§16.4 claims: "same input → same tick ordinal → same reap and inference events → same hash." The last arrow is invalid. The hash covers execution_heat, which is co-written by two streams — word executions (increments) and engine ticks (decay). Once ticks come from a hardware timer, where tick N lands relative to the instruction stream is wall-clock-dependent: under TCG, run A takes tick 42 after word #1000, run B after word #1017. Decay interleaves differently, heat trajectories diverge, hashes differ. Firing on tick count fixes the engine's schedule; the hash measures the composition of the two streams, and that is not fixed.

Blast radius:

• Item 0.8 is ambiguous between two different kernels. Reading (i): the bottom half services only TIME-TRUST bookkeeping — safe, parity holds, but "compudynamics on the tick" did not actually happen. Reading (ii): the bottom half drives the engine/decay from the hardware tick — parity breaks by construction, not by implementation error.
• Item 0.10's double-boot dict-hash check then fails under reading (ii), and no implementation effort can fix it.
• Item 2.1's corrected acceptance (identical fleet heat sum across runs) is still unachievable under a hardware tick: touch amounts scale with elapsed ticks between fixed execution points, elapsed ticks vary run to run, so truncation losses vary, so the sum varies. The first review's amendment did not go far enough.
• The tempting split does not survive either. "Hash-covered state on execution ticks, TTLs on hardware ticks" fails because TTL expiry has side effects on the instruction stream — a message expiring versus being delivered changes what runs, which corrupts heat downstream. §17.1's "one tick" instinct was right; it picked the wrong clock.

Recommended resolution (not decided): the engine's tick is a virtual tick — a pure function of the execution stream, which is exactly what exists today and why parity holds today. The hardware heartbeat becomes: the TIME-TRUST instrument (now real on three ISAs instead of one), the idle wake source, and the driver of nothing that feeds patron state. Scripted/parity runs stay bit-identical; interactive idling pumps virtual ticks from the REPL poll loop so TTLs still expire in real time, in a context where parity was never claimed. Phase 0's timer work remains fully justified as instrument and substrate. Under this ruling §16.4, §17.1, §18.4 and items 0.8, 0.10, 2.1 all need rewording. The alternative — re-baselining the parity claim itself — touches the patent support material and is not recommended.

GAP-B — unverified prerequisites (each is a short read; none has been done)

• B1 — Device tree reachability. Items 0.3 and 0.6 instruct "read from the device tree" (0.6 forbids alternatives). Whether the loader captures the DTB from the EFI configuration table into BootInfo is unverified. If it does not, 0.3 and 0.6 silently require loader plumbing that has no punch item. Read uefi_loader.c / BootInfo first.
• B2 — FP/SIMD in the ISR path. Items 0.2 and 0.5 save integer state only. If the kernel is not built with -mgeneral-regs-only (aarch64) / soft-float (riscv64), a C interrupt handler may clobber FP registers the interrupted mainline was using. One grep of Makefile.starkernel settles it; the items should carry the check.
• B3 — 0.4's EL detection does not govern the vector path. 0.4 refuses to hardcode the EL for timer registers, but 0.5 hardcodes ELR_EL1/SPSR_EL1/eret, and today's isr.S installs VBAR_EL1. If EDK2 leaves the kernel at EL2, exceptions vector through VBAR_EL2 and 0.5's entire edit targets a table that is never consulted. EL determination must govern VBAR, the saved-state register forms, and the timer set.

GAP-C — defects in punch items a literal implementer will hit

• C1 — Item 0.1 contradicts itself. Body says remove "blocks 2050–2059"; Refs says block 2050 survives. The delete set is 2051–2056 + 2058–2059; 2050 is edited (banner call kept, handshake/broadcast calls removed). A literal reading deletes the banner.
• C2 — Items 0.2 and 0.5 have unsatisfiable acceptance. Both require having "taken and returned from at least one trap/IRQ," but at 0.2 no timer is armed (0.3) and at 0.5 there is no GIC (0.6) and no armed timer (0.7). No interrupt source exists at those stages. Fix: 0.2/0.5 accept on "boots unchanged, no regression"; the took-and-returned evidence moves to 0.3/0.7.
• C3 — Item 0.3 lost the two silent-failure modes. The SBI timer is one-shot: a missed re-arm stops the heartbeat forever with no error. sie.STIE is also unmentioned. 0.7 says "re-armed each tick"; 0.3 must too.
• C4 — §23.4 #4 blocks item 3.1 but is not a punch item. The continuation-cell encoding gates 3.1 by 3.1's own text, but rule 1 walks numbered items and nothing ever schedules it. It should become item 1.12.
• C5 — Item 1.11's deferral is not a formal prerequisite. It says "do not settle speculatively" but states no blocker, so rule 1 would schedule it. Add "(blocked on 4.3)."
• C6 — Item 0.10 misc. "amd64 output unchanged" treats amd64 as a control, but 0.8 changes amd64's engine plumbing by design — stale framing. "TIME-TRUST and variance sane" is soft; sharpen to trust near Q48_ONE, variance small relative to the new expected_delta.
• C7 — The commit template hardcodes "Claude Opus 5." Whichever model implements will either violate the template or misattribute. Genericize.

GAP-D — inconsistencies left by the layered amendments

• D1 — Three passages still argue from the K-justification the first review removed. §17.3 ("wastes the bounded capacity that gives K a fixed denominator"), §17.5's sizing argument (same phrase), and §17.6(d) — the worst, since it cites §2 for a claim §2 now explicitly disavows ("Without an inescapable bound, K is bookkeeping — §2 says this in as many words").
• D2 — §19.6 #1 and #2 read as open but are resolved (#1 by §23.1 with the residue in §23.4 #4; #2 by §24.3). §17.4 got strike-through treatment; §19.6 did not.
• D3 — §20.3 still says "LEANING nested" one section before §21 decides it. One forward pointer fixes it.

What held up under this pass

The patron taxonomy, behaviours-not-kinds dispatch, the three quantities, the two-valued cell union, the nested-elastic-quota layout, the identity/mass invariant, Hera's pin-and-panic, and §25.0's rules themselves. None of them moved.

Triage order when this is picked up: rule on A1 first — it decides what item 0.8 even means. B1/B2 are ten-minute reads. C and D are mechanical once A1 is ruled. Nothing should go to a coding model before C1, C2 and C3 are fixed at minimum — those are the ones it will hit in its first hour.

---

26. The hardware heartbeat must itself be adaptive — RULED 2026-08-03

Raised mid-0.8: the punch list, as written, makes the hardware tick a fixed-rate instrument (100 Hz, unconditionally, on all three architectures — the apic_timer_init(..., 100) calls built across items 0.1–0.7). That is correct for what §18.4/§18.5 require of the engine — the virtual tick stays execution-paced regardless. But it leaves the physical heartbeat monotonic, and the physical heartbeat was never supposed to be monotonic. Captain Bob: "the heartbeat is adaptive... it spreads the heartbeat out when your heart goes faster when you're running... it's gotta be an adaptive heartbeat, that's the whole thing to cage variance."

26.1 The finding — an adaptive-rate engine already exists, and it is orphaned

vm_runtime.c:703-752 ("Loop #7 — Adaptive Heartrate") computes a bounded adaptive period, vm->heartbeat.tick_target_ns, from the same ANOVA-driven stability signal Loop #5 already uses: early-exit (stable) slows it down, full-inference (volatile) speeds it up, ±25% per step, clamped to [¼×, 4×] of a configured base. This is real, executing code, faithful to the design in the sibling StarForth repo's own docs/working/architecture/03-architecture/heartbeat-system/architecture.md (Option A vs. Option B). It is not a proposal — it already runs, on every vm_tick().

It is orphaned. tick_target_ns is written to vm->heartbeat.worker->tick_ns (include/vm.h:286,289), and worker is always NULL in kernel builds — nothing in src/starkernel/ reads tick_target_ns at all. The mechanism that was meant to consume it, a pthread_create()-based background worker (heartbeat_thread_main(), vendored into vm_bootstrap.c:310), is deliberately and redundantly disabled for kernel builds (Makefile.starkernel:293,338, HEARTBEAT_THREAD_ENABLED forced to 0 twice) — correctly: this is a bare-metal single-hart kernel, there is no pthread implementation, and the mechanism's own history (segfault-analysis.md in the StarForth repo) is a real concurrent-access bug against RollingWindowOfTruth, fixed by a mutex a single hart doesn't need and can't cheaply provide (§21.2, item 0.9).

So: the decision logic is real, tested by inheritance, and currently produces a number nothing downstream ever reads. Phase 0 as written would ship a heartbeat that looks adaptive in the source tree and is not adaptive on the wire.

26.2 This does not reopen GAP-A1

§18.5 already proved the general shape of this argument for Loop #5 and is directly reusable for Loop #7: adaptation is safe exactly when its inputs are execution-derived, because then the decision to change the period is itself a deterministic function of the execution stream, not of wall-clock jitter. §18.5 point 3 already establishes that every InferenceInputs field feeding this ANOVA machinery — rolling window, trajectory length, prefetch hit rate, hot/stale word counts, total heat, word count — is execution-derived with zero timing input. Loop #7's stable/volatile classification is downstream of that same machinery. Nothing new needs proving there.

What must not change, and does not under this design:

• The virtual tick stays the engine's clock (§18.4, unchanged). Adjusting the physical re-arm period changes when TIME-TRUST samples land and how often the idle path wakes — it does not move decay, reap, or inference off the virtual tick onto the hardware one.
• The hardware tick's output still feeds nothing that reaches the parity hash (§18.5 points 1, 5, unchanged) — only its input (the period it's told to re-arm at) becomes execution-derived instead of fixed.
• What was already true and already inert under §18.5 — that wall-clock interrupt arrival timing is not reproducible run to run — stays true and stays inert. Nothing patron-facing ever depended on it; this design doesn't change that.

26.3 The scale mismatch, and the ruling

tick_target_ns's configured base, HEARTBEAT_TICK_NS (include/starforth_config.h:71), is 10000ULL — 10 microseconds. Its live range under Loop #7's ±25%/[¼×,4×] bounds is therefore 2.5µs–40µs. The hardware timer configured throughout items 0.1–0.7 runs at 100 Hz — 10 milliseconds. That is a three-orders-of-magnitude mismatch: reprogramming the physical re-arm to the literal tick_target_ns value would fire the timer 25,000–400,000 times a second, which on a bare-metal single-hart kernel means the core spends effectively all its time in trap entry/exit and the REPL is never reached. HEARTBEAT_TICK_NS was tuned for a hosted OS thread's sleep granularity, not a bare-metal ISR period.

RULED (Captain Bob, 2026-08-03): same relationship, kernel-appropriate scale. The mechanism must be real and load-bearing — a genuine, measurable effect on the physical re-arm period, the same kind of effect the original hosted pthread experiments showed — but computed against the 10 ms / 100 Hz base already established for this kernel, not the 10 µs hosted base. Loop #7's decision logic (stable → slower, volatile → faster, ±25% per step, clamped [¼×, 4×]) is reused unmodified; only the base it is applied to changes.

26.4 The mechanism — no thread needed

Captain Bob authorized building a kernel-native thread/task if one were required ("if we gotta run a thread or whatever, it doesn't matter"). One is not required, and adding one would need a preemptive scheduler this single-hart kernel does not have (§21.2 already rules out real locking for exactly this reason). The existing shape gets there without new infrastructure:

• vm_tick() already calls Loop #7 on the mainline path (execution-paced, never in interrupt context) and already produces a fresh tick_target_ns there.
• Item 0.8 already introduces a shared heartbeat.c owning the top/bottom-half split. That file is the natural owner of one new piece of state: the current adaptive period, set by a new heartbeat_set_adaptive_period_ns(uint64_t ns) (called from vm_runtime.c's Loop #7 site, scaled to the kernel base per §26.3) and read by a new heartbeat_next_period_ns(void).
• Each architecture's existing re-arm function (apic_timer_rearm(), riscv64_timer_rearm(), the aarch64 equivalent) already runs in interrupt context at the top of every tick (§18.4's "one tick" call sites, unchanged). It converts heartbeat_next_period_ns() to that architecture's raw counter units — a conversion each already does today for its fixed period — instead of using a hardcoded constant.

No new concurrency: the write happens on the mainline execution path, the read happens in interrupt context, and the value read is whatever was last written — the same single-writer/ single-reader shape every other piece of ISR-read, mainline-written state in this kernel already has (§21.1's finding that locking here is already free, because nothing here is actually concurrent on one hart). No pthread, no kernel task, no scheduler.

26.5 Open, deferred

• Multi-VM: today Hera is the only VM, so "whose tick_target_ns drives the one physical timer" has one answer. Not resolved for when Hermes/Artemis return — deferred, not applicable yet (consistent with §20.5's other Tripod-return deferrals).
• HEARTBEAT_TICK_NS's name and its hosted-scale value are unchanged by this ruling — the kernel-side base (10 ms) is a separate constant, not a redefinition of the hosted one. Naming the kernel constant is an implementation detail of the item that builds this, not a document-level open question.

RULED. Item 0.8 is amended below to include this; no new punch-list item is needed — this is squarely inside what 0.8 already builds (heartbeat.c, the three re-arm call sites).