chore(agents): restore evidence sharing after the asset purge

Issue #49 removed game assets from git. It also, silently, removed the only
transport agents had for showing each other evidence: each agent works in its
OWN clone, so "commit the screenshot, the other one pulls it" was the mechanism,
and PROTOCOL.md's file table said so in as many words -- "evidence cited by a
finding -> git". That row sat directly above "🔴 Never commit game content",
which is how 76 MB accumulated: the two contradicted each other and the table
won, because it was the one that told you what to do.

WHAT REPLACES IT

  * one host directory, `Sylpheed/docs/re/captures/`, bind-mounted read-write
    into BOTH agents at /work/docs/re/captures. All three -- host, decoder,
    port -- see the same files live, every citation resolves, and nothing can
    reach git history. Read-write on purpose: showing each other a screenshot
    is the point.
  * PROTOCOL.md's table rewritten. Cited evidence -> present but never
    committed; derived measurements (csv/tsv/txt/log/json) -> still git, they
    are our numbers not game content; evidence that must cross MACHINES ->
    attached to the issue or PR, because a bare clone has no captures.

Verified, not assumed: container A wrote a .png there, a SEPARATE container B
read it back, the host saw it, `git status` reported 0 changes, and
`git check-ignore` named the rule.

THE CHECKER WAS RED ON EVERY CLEAN CHECKOUT

A fresh clone/worktree/CI has no captures, so it called all 134 citations
dangling and exited 1. A gate that is red before anyone changes anything is one
people learn to ignore -- the exact failure this file already carries a comment
about. It now distinguishes "no captures here" (expected, explains itself,
exit 0) from "these are missing" (real, exit 1, unchanged when assets ARE
present). Both paths tested.

ALSO
  * `sylph-decoder` no longer mounts `xenia-rs` -- retired repo, gone from disk,
    the mount pointed at nothing.
  * CONSOLIDATION.md closed: it still described captures as committed and the
    history fork as undecided. Both are settled.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/agents/CONSOLIDATION.md

@@ -1,3 +1,27 @@
+# ✅ CLOSED 2026-09-20 — every phase done, and the two human decisions taken
+
+Nothing on this page is outstanding. It is kept as the record of how the two-repo
+layout was reached; **where it describes the repository's present state it is
+now out of date on purpose**, and the notes below say how.
+
+| the page says | what is true now |
+|---|---|
+| "**Still open, for the human**: the history fork" | **Taken: full purge.** `git filter-repo` stripped 182 assets from every commit; force-pushed 2026-09-19. `main` `2a93be99` → `e16556dc`, `.git` **217 MB → 114 MB**, **0** assets anywhere in history, verified from an independent fresh clone. Backups + runbook: `~/sylph-repo-backup-2026-09-19/` |
+| "`docs/re/captures/` is 118 MB of game screenshots inside a public repository" | **Decided (#49): no game assets in the repos.** Captures live on disk, gitignored, shared between the host and both agents by bind mount; derived measurements (csv/tsv/txt/log/json/npy) stay tracked. PR #59 |
+| "all six repos are `private=False`" | Still true, and now deliberate — there is nothing game-derived in them |
+| "`ai-agent-*.md`, `scratch/`, `_voice_span.rs` — keep or drop" | `scratch/` and `_voice_span.rs` dropped in the 2026-09-18 cleanup; the `ai-agent-*.md` files are the human's and stay |
+| the four archived repos | unchanged: `Sylpheed-Godot`, `xenia-rs`, `xex2tractor` archived read-only, `Syplheed-Reborn` deleted. ⚠️ Their local clones are **gone from this machine** too, and `sylph-decoder` no longer mounts `xenia-rs` |
+
+🔴 **The one thing this page got right and nobody acted on.** It named
+`crates/sylpheed-export`'s dependency on **this repository by tag** as the hard
+blocker for a rewrite. It was not re-checked before the purge, the locked rev
+vanished, and the build broke for every clean checkout while still working on the
+machine that did the rewrite — its `~/.cargo/git` still held the old object.
+Fixed in PR #60 (re-lock) and PR #61 (path dependency, which removes the class).
+**Before any future history rewrite, grep for a dependency on the repo's own URL.**
+
+---
+
 # Consolidating six repositories into two
 
 **Set by the human, 2026-09-13.** The end state is **two** repositories: