fix: read the turn's environment across a native compaction summary

[felixlark]

Problem

Every turn after an automatic compaction fails:

stream disconnected before completion: ChatGPT web turn is missing cwd in trusted Codex environment context

Codex 0.155 rebuilds a compacted turn in this order (observed on a real thread, 7 input items):

#	role	content
1	developer	additional_tools
2-3	developer	preamble
4	user	the turn's message — parts are plugins.recommendations, agents_md.instructions, environments.environment_context
5	user	the compaction summary
6	developer	world state
7	user	the instruction being answered

canonicalMetadataEnvironmentBeforeUser() walks back from item 7 and skips only developer messages, so item 5 ends the search. Item 4's envelope — the one that carries cwd — is never read, and the turn is refused. Codex then retries five times and gives up.

The envelope itself is well-formed; nothing is wrong with the request except the position of the summary.

Change

Skip a compaction summary while walking back, exactly as a developer message is skipped, under the same provenance rule: its turn id must match the canonical turn, or it must carry a server-owned item id. A summary is recognized by the same predicate the code already uses elsewhere (isReadableCompactionSummaryText / OPAQUE_COMPACTION_NOTE).

This does not widen what can become authority:

• the summary is never itself read as an environment,
• any other user message between the envelope and the instruction still ends the search,
• the envelope still has to pass environmentMatchesCanonicalMetadata.

Tests

tests/environment.test.ts:

• the exact shape above resolves the environment (fails without the change, with the original missing-cwd error),
• a summary stamped with a different turn id is not skipped, so the turn is still refused.

bun test tests/environment.test.ts tests/thread-environment.test.ts on top of main: 63 pass, 1 skip, 0 fail.

How it was found

The bridge logged nothing when it refused a turn, so this could only be placed by reproducing it against a real thread and instrumenting the refusal path. If you want, I can send that diagnostic (which branch refused, plus the input's shape — types, roles, sizes, whether a part holds an envelope; never prompt text) as a separate PR; it turned a five-retry mystery into a one-line answer.

🤖 Generated with Claude Code

[felixlark]

Pushed a second commit: the same failure has a second shape, seen on another thread today.

A compacted turn does not always end with a fresh instruction. Thread 01a0bf61 sent five items:

#	role	content
1-3	developer	additional_tools + preamble
4	user	the turn's message — parts are plugins / AGENTS.md / environment_context
5	user	the compaction summary, and it is what the model is asked to continue from

So the anchor canonicalMetadataEnvironmentBeforeUser() walks back from is item 4 — the envelope message itself — and the function only ever inspected messages before the anchor. Same user-visible error.

The new commit checks the anchor's own content parts before walking back, and allows index 0 as an anchor for the same reason. The envelope still has to bind to canonical turn and sandbox metadata, so this widens where the envelope may sit, not what it may claim. A test reproduces the five-item shape and fails without the change.

bun test tests/environment.test.ts tests/thread-environment.test.ts on top of main: 64 pass, 0 fail.