Codex 0.145 re-fires SessionStart with source:"compact" after every
context compaction, and injects hook stdout into the live model context
(both verified with sentinel probes on codex-cli 0.145.0). Compaction
replaces the transcript with a summary that sheds the using-superpowers
bootstrap and the active skill's instructions; in instrumented SDD runs
the first post-compaction dispatch that lacked a freshly printed
reminder reverted to harness defaults (fork_turns=all, inherited
frontier model) and the drift then self-perpetuated. Claude Code never
exhibits this because its SessionStart matcher (startup|clear|compact)
re-injects the bootstrap at the same moment — this hook restores that
parity on Codex.
On source:"startup" the hook emits nothing: the native plugin path owns
session-start injection, and duplicating it would recreate the
redundancy that led to the original session-start-codex removal. Output
is plain text (Codex consumes raw stdout, unlike the JSON envelopes
hooks/session-start emits for other harnesses), and every failure path
is fail-open: bad stdin, missing skill file, or any error yields empty
output and exit 0 so a hook problem can never break a session.
Ships with hooks-codex.json.example for the user-level ~/.codex/hooks.json
merge and tests covering source filtering, whitespace-tolerant matching,
decoy fields, and fail-open behavior.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
hooks/session-start-codex has had no caller since "Remove Codex hooks"
(#1845) deleted hooks-codex.json and its manifest registration; the
Codex manifest now declares an empty hooks object so Codex registers no
session-start hook at all. The script is Codex-specific dead code —
nothing executes it on Codex or any other harness.
- Delete hooks/session-start-codex.
- tests/hooks/test-session-start.sh: drop the two Codex cases that are
redundant with the generic session-start tests (nested-format and the
legacy-warning omission are already covered by the Claude Code cases).
Re-point the "wrapper dispatches" case to the live `session-start`
script so run-hook.cmd dispatch coverage — used by Claude Code and
Cursor in production — is preserved rather than lost.
- docs/porting-to-a-new-harness.md: Codex is no longer a Shape A
(shell-hook) harness, so re-anchor that worked example to Cursor (a
live shell-hook harness that demonstrates the same per-harness field,
schema, and matcher variance) and mark Codex as native skill discovery
with no session-start hook. Clears the references to the deleted
hooks-codex.json.
- docs/windows/polyglot-hooks.md: the "check hooks-codex.json" pointer
referenced a file deleted in #1845; re-point to hooks-cursor.json.
RELEASE-NOTES.md keeps its historical mention of hooks-codex.json (it
accurately records what that release did). The tests/codex-plugin-sync
fixtures build their own synthetic session-start-codex and test the sync
mechanism generically, so they are intentionally left as-is.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
On Windows + Git Bash, the SessionStart hook prints a confusing
diagnostic at every startup ("printf: write error: Permission denied")
when Claude Code closes the hook's stdout pipe before the printf has
finished writing. The hook still runs to completion and context still
gets injected, but the diagnostic surfaces every session because
Git Bash's printf reports EPIPE as "Permission denied" (not "Broken
pipe" like Linux) and our `set -euo pipefail` lets that error escape.
Piping each printf through `cat` makes the external cat process the
recipient of any SIGPIPE / EPIPE. cat's failure does not propagate to
the parent bash under pipefail because cat is the last command in the
pipeline and exits cleanly when the pipe stays open long enough to
hold the data. On macOS/Linux the cat passthrough is transparent (no
behavior change, no measurable cost).
Verified:
- Existing tests/hooks/test-session-start.sh: 7/7 pass on macOS
- Manual run on Windows 11 + Git Bash 5.2 + Node 22 produces valid JSON,
clean stderr, and exit 0
- JSON output is byte-identical to the unpatched hook
Reported by @silvertakana in #1612, attribution preserved in the
Co-authored-by trailer below — this is the same fix shape the original
PR proposed.
Co-authored-by: silvertakana <silvertakana@users.noreply.github.com>
Closes#1612.
