v1.55.1.0 fix: telemetry consent accuracy + gstack-slug cache sanitization (#1848)

* fix(gstack-slug): sanitize cached slug before eval

The compute and fallback paths filter slug output to [a-zA-Z0-9._-], but a
value read straight from ~/.gstack/slug-cache was echoed into eval output
unsanitized. A locally-planted cache file could inject shell into
eval "$(gstack-slug)". Re-sanitize on every path so the invariant the file
header promises actually holds, and heal a poisoned cache on the next write.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(telemetry): accurate consent copy + JSON-safe repo basename

The telemetry consent prompt promised "no repo names" while the preamble
epilogue records the repo basename in the local skill-usage.jsonl. It is
already stripped before any remote upload, so it never left the machine, but
the copy was unqualified. Reword it to state repo name is local-only and
stripped before upload.

Also sanitize the basename to [a-zA-Z0-9._-] before it goes into the
hand-built JSON, so a repo directory name containing quotes or newlines can
neither break the JSON nor leak a fragment past the regex stripper.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore(docs): regenerate SKILL.md + ship goldens for telemetry change

Generated output of the preceding resolver change: the corrected consent copy
and sanitized repo basename now appear in every skill preamble. Golden ship
fixtures refreshed to match.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test(telemetry): enforce no-repo-identity-egress invariant

Pins the contract that repo/branch identity in the synced skill-usage.jsonl is
stripped before the remote POST. Three checks: a floor (the three known fields),
coverage (every repo/branch field a producer writes into skill-usage.jsonl is
stripped, so a future producer rename can't silently leak), and behavior (runs
the actual sed strip expressions over a sample event). Scoped to the synced
file, so the local-only timeline branch field is correctly excluded.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test(gstack-slug): regression test for cached-slug eval injection

Proves a poisoned ~/.gstack/slug-cache file cannot inject shell metacharacters
into gstack-slug output (the value consumed by eval). Verified red when the
cache-read sanitization is removed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v1.55.1.0)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

qa-only/SKILL.md

@@ -63,7 +63,7 @@ _QUESTION_TUNING=$(~/.claude/skills/gstack/bin/gstack-config get question_tuning
 echo "QUESTION_TUNING: $_QUESTION_TUNING"
 mkdir -p ~/.gstack/analytics
 if [ "$_TEL" != "off" ]; then
-echo '{"skill":"qa-only","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true
+echo '{"skill":"qa-only","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(_repo=$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null | tr -cd 'a-zA-Z0-9._-'); echo "${_repo:-unknown}")'"}'  >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true
 fi
 for _PF in $(find ~/.gstack/analytics -maxdepth 1 -name '.pending-*' 2>/dev/null); do
   if [ -f "$_PF" ]; then
@@ -173,7 +173,7 @@ Only run `open` if yes. Always run `touch`.
 
 If `TEL_PROMPTED` is `no` AND `LAKE_INTRO` is `yes`: ask telemetry once via AskUserQuestion:
 
-> Help gstack get better. Share usage data only: skill, duration, crashes, stable device ID. No code, file paths, or repo names.
+> Help gstack get better. Share usage data only: skill, duration, crashes, stable device ID. No code or file paths. Your repo name is recorded locally only and stripped before any upload.
 
 Options:
 - A) Help gstack get better! (recommended)