FABRIC-3.md §I.4: magic-number content-type detection, closing Milestone 6

Closes both remaining Milestone 6 (PKI) punch-list items.

Signature-status column: doc-only closure -- the underlying need was
already redirected to capsules/BLOCK_MAP.md's real Signed column
(2026-08-26); checking the box off as moot-as-worded rather than
leaving an accurate-but-permanently-unchecked marker.

Magic-number content-type detection (Section U item 14): built in
tools/mkcapsule.c. detect_content_type() classifies a file's actual
leading bytes (TTF/OpenType sfnt tags, DER's 0x30 SEQUENCE tag, or a
printable-ASCII/TAB/CR/LF heuristic for text) against
expected_type_from_ext()'s .4th/.md/.der/.ttf mapping; process_file()
warns on mismatch, never refuses -- same WARN-first rollout this
project already used for capsule signing. Verified against every real
capsule in the repo (38 files) with zero false positives. This is the
shared primitive Milestone 7's contrib-capsule validation can reuse
next.

Verified 3-arch boot to ok> (amd64/aarch64/riscv64, each in the
foreground); logs and DoE CSVs from this session's verification runs
included per this repo's own audit-artifact convention.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019YcT3H2PQeyujrzjqS3Var

This commit is contained in:

Robert Allan James

2026-09-04 10:45:57 -04:00

co-authored by

Claude Sonnet 5

parent 4018fe8b04

commit 5567d03c12

10 changed files with 27697 additions and 12 deletions

									
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				# Capsule Block Manifest — Auto-generated

				<!-- Generated by mkcapsule --manifest  2026-09-04T14:30:04Z -->

				<!-- Generated by mkcapsule --manifest  2026-09-04T14:43:57Z -->

				<!-- DO NOT EDIT — re-run mkcapsule --manifest to refresh.  -->

				<!-- Hand-written justifications and immutability notes live  -->

				<!-- in MANIFEST.md alongside this auto-generated index.      -->