Admit codex-cli 0.151.0

[schickling-assistant]

Problem

st2's fail-closed native Codex driver rejects the installed codex-cli 0.151.0 before app-server initialization because the exact protocol allowlist stops at 0.147.0.

Goal

Admit exactly codex-cli 0.151.0 after source and live-wire verification, while keeping later versions rejected until independently proven.

Decisions

• Keep the exact string allowlist; no semver range or compatibility fallback.
• Re-pin context arithmetic to the 0.151.0 source tag after verifying the 12,000-token baseline is unchanged.
• Preserve the existing loose handling of additive notifications and update the ThreadItem note from 18 to 19 variants.
• Record only the live receipt path actually observed: the initial native turn completed, and restart reconciliation accepted the matching clientId from typed thread/resume history. The live item/completed notification did not independently advance the persisted receipt before restart.

Verification

• cargo test -p st2 --lib codex_app_server::tests::protocol_version_gate_accepts_only_the_exact_allowlist -- --exact: 1 passed.
• cargo test -p st2 --lib codex_app_server::tests::codex_context_recomputes_the_captured_reading_and_pins_its_verified_version -- --exact: 1 passed.
• Installed codex --version: codex-cli 0.151.0.
• Real native driver proof: exact version gate passed; control reached controlInitialized; a fresh thread bound; st2 submitted a native turn/start; Codex completed the turn; a deliberate driver restart reached tuiThreadLoaded/threadBound, subscribed via thread/resume, found the matching typed-history clientId, and persisted delivery phase accepted. The account had quota and both model turns completed.

Complexity

No new abstraction or dependency; this is an exact admission plus evidence/test/documentation updates.

Concerns

The live item/completed notification did not independently move the receipt from attempted before restart. Durable thread/resume reconciliation did move it to accepted, so the proven receipt path is restart-backed rather than notification-backed.

PR #386 overlaps this file and proposes replacing the exact gate with generated schema checks. This PR intentionally retains the current fail-closed exact admission policy; merge order will require an explicit policy choice.

Friction & bottlenecks

The default Codex app-server control path is a symlink in this environment, while Codex requires the path itself to be a directory. The live proof used the already-resolved account home; no repository workaround was added. No measurable bottleneck was encountered.

Follow-ups

• Determine why the live typed item/completed notification did not independently advance the receipt; this does not block the proven durable resume-reconciliation path.

References

Refs #267
Related: #386

Posted on behalf of @schickling

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