The SessionStart hook injects the most recent *-session.tmp as
additionalContext labelled only with 'Previous session summary:'.
After a /compact boundary, the model frequently re-executes stale
slash-skill invocations it finds inside that summary, re-running
ARGUMENTS-bearing skills (e.g. /fw-task-new, /fw-raise-pr) with the
last ARGUMENTS they saw.
Observed on claude-opus-4-7 with ECC v1.9.0 on a firmware project:
after compaction resume, the model spontaneously re-enters the prior
skill with stale ARGUMENTS, duplicating GitHub issues, Notion tasks,
and branches for work that is already merged.
ECC cannot fix Claude Code's skill-state replay across compactions,
but it can stop amplifying it. Wrap the injected summary in an
explicit HISTORICAL REFERENCE ONLY preamble with a STALE-BY-DEFAULT
contract and delimit the block with BEGIN/END markers so the model
treats everything inside as frozen reference material.
Tests: update the two hooks.test.js cases that asserted on the old
'Previous session summary' literal to assert on the new guard
preamble, the STALE-BY-DEFAULT contract, and both delimiters. 219/219
tests pass locally.
Tracked at: #1534
- Route the transcript-derived shortId through sanitizeSessionId so the
fallback and transcript branches remain byte-for-byte equivalent for any
non-UUID session IDs that still land in CLAUDE_SESSION_ID (greptile P1).
- Clarify the inline comment in the first regression test: clearing
CLAUDE_SESSION_ID exercises the transcript_path branch, not the
getSessionIdShort() fallback (coderabbit P2).
Refs #1494
- Use last-8 chars of transcript UUID instead of first-8, matching
getSessionIdShort()'s .slice(-8) convention. Same session now produces the
same filename whether shortId comes from CLAUDE_SESSION_ID or transcript_path,
so existing .tmp files are not orphaned on upgrade.
- Normalize extracted hex prefix to lowercase to avoid case-driven filename
divergence from sanitizeSessionId()'s lowercase output.
- Explicitly clear CLAUDE_SESSION_ID in the first regression test so the env
leak from parent test runs cannot hide the fallback path.
- Add regression tests for the lowercase-normalization path and for the case
where CLAUDE_SESSION_ID and transcript_path refer to the same UUID (backward
compat guarantee).
Refs #1494
