SessionStart exit-2-as-advisory no longer reaches the user. abcd hook session-start returns exitError{Code: 2} whenever it has notices to print (internal/surface/cli/cli.go:1289), on the documented assumption that a non-zero SessionStart surfaces stderr without blocking. Claude Code v2.1.241 instead renders it as 'SessionStart:startup hook error' followed by a truncated echo of the hooks.json command string; the stderr notice itself never reaches the user. Every session-start notice is therefore an opaque error banner: transcript-capture gaps, staged-drain failures, the remaining-backlog count, binary skew, dogfood staleness, and the version transition. The data-loss-adjacent ones matter most - a user told that a session transcript was not captured now sees only a hook error, with no way to learn what it was.

Frontmatter

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mentions5

• iss-2608251011427187hooks/bootstrap.sh and hooks.json still deliver SessionStart notices by a non-zero exit, which the harness renders as an opaque banner with the text dropped. iss-2608241115201044 fixed the binary half: abcd hook session-start now exits 0, writes its notice text to stderr and only a CONSTANT to stdout. The shell half is unchanged and inconsistent with it. bootstrap.sh's notice() exits 2 on a REPORTED CONDITION including a successful install, and hooks.json's SessionStart chain propagates that ($s) plus a trailing exit 2 on the missing-binary branch. Under the same premise those messages are dropped too, so a fresh install's success line and the missing-binary complaint are both delivered by the mechanism the binary half abandoned. bootstrap.sh's own comment states the reasoning that makes the binary fix correct — 'a SessionStart hook's stdout becomes model context' — and an adversarial review demonstrated that concern concretely, planting a directive payload in a TRACKED config value that reached context when notices were briefly routed to stdout. So the shell must NOT simply move its text to stdout either. The open question is what channel a shell hook has left: a constant on stdout plus text on stderr mirrors the binary, but bootstrap.sh's exit code also governs the install path, and changing it touches the most safety-critical surface in the repo. Deliberately deferred rather than bundled into the binary fix.
• iss-2610161125115941hooks/session-start.sh runs the session-start entrypoint even when hooks/bootstrap.sh failed but a plugin binary is present, then exits with bootstrap's non-zero code: the host shows its empty 'startup hook error' banner and drops the notices the entrypoint just printed, the outcome iss-2608241115201044 fixed for the entrypoint's own exit.
• iss-2610161125118921The comment above the session-start hook in internal/surface/cli/cli.go (around lines 2006-2015) still says the loud path deliberately exits 2, while the code below it exits 0 on every path and a later comment says so (iss-2608241115201044).
• itd-2610161617096084After a plugin update, abcd says what changed for this repository
• spc-2610170635097509after-update