fix(#381): make gsd_run launcher reachable in fresh-shell-per-block runtimes (#1084)

* fix(#381): make gsd_run launcher reachable in fresh-shell-per-block runtimes

On runtimes that execute each fenced bash block in a separate shell process
(e.g. Claude Code — documented behavior: each Bash command is a separate
process; inline shell functions and exported vars do not persist between
calls), the once-per-file gsd_run() function was undefined in every block
after the preamble block, and the call was swallowed by
`2>/dev/null || echo "{}"` into silent empty state.

Fix (budget-neutral session-level resolution):
- Ship gsd-core/bin/gsd_run, a POSIX sh wrapper that symlink-resolves its own
  location and execs the co-located gsd-tools.cjs. Exposed on PATH via the npm
  `bin` field (global installs) and shipped to local installs via the recursive
  gsd-core/ copy.
- The per-file launcher preamble now appends `export PATH='<bindir>':"$PATH"`
  to the file named by $CLAUDE_ENV_FILE (Claude Code's documented
  env-persistence mechanism) so later fresh-shell blocks resolve gsd_run from
  PATH. Guarded as a strict no-op when CLAUDE_ENV_FILE is unset; the inline
  gsd_run() definition remains the fallback for all other runtimes. The
  single-quoted dir neutralizes shell metacharacters at source time.
- Propagated via scripts/sync-runtime-launcher.cjs to all launcher-using files.
- XL workflow byte budget 93000 -> 93200 (the ~130B clause pushes plan-phase.md
  to 93135; legitimate content growth, ratchet-up per #717).

Regression tests (I)/(J) in runtime-launcher-parity.test.cjs cover wrapper
delegation and end-to-end PATH persistence (sourcing the env file with a
space-bearing install path).

Known limitation: an install path containing a literal single-quote yields a
malformed env-file line and falls back to the status quo (no regression);
rare on sanitized home directories.

Closes #381

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* docs(#381): add changeset for gsd_run fresh-shell reachability fix

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test(#381): scope test (J) bare-PATH execution to POSIX (Windows Git Bash exec bit)

Windows Git Bash (msys2) does not honor Node's chmod exec bit for
PATH-executing extension-less scripts, so the bare `gsd_run` command lookup
failed there even though the env-file PATH persistence was correct. The
env-file content assertions (the fix's actual cross-platform logic) still run
on every platform; only the final source-and-execute sub-step is gated to
non-win32. Global installs on Windows are covered by npm's generated bin shim.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/workflow-size-budget.test.cjs

@@ -81,9 +81,10 @@ const GRACE = 3000;
 // current high-water mark within GRACE (#597 tighten-only ratchet).
 // XL high-water mark is execute-phase.md — note that under LINES it was
 // plan-phase; bytes genuinely re-rank the tier, which is the point of #717.
-// actualMax=92525 (execute-phase, #913 inline-fallback scope clarification);
-// slack=475 ≤ GRACE. plan-phase.md=90748 (#922 attempt-based Agent gate), new-project.md=58110.
-const XL_BUDGET = 93000;
+// actualMax=93130 (plan-phase, #381 CLAUDE_ENV_FILE persist clause in per-file launcher preamble);
+// slack=70 ≤ GRACE. execute-phase.md=92880, new-project.md=61685.
+// 93200: +200B headroom for the #381 CLAUDE_ENV_FILE persist clause added to every per-file launcher preamble (legit content growth, ratchet-up per #717).
+const XL_BUDGET = 93200;
 // LARGE high-water mark is docs-update.md. actualMax=54410 (#891 launcher shim expansion);
 // slack=1590 ≤ GRACE. quick.md=45710, autonomous.md=38030.
 const LARGE_BUDGET = 56000;
@@ -95,9 +96,9 @@ const DEFAULT_BUDGET = 40000;
 // Grandfathered at current sizes — see PR #2551 for the progressive-disclosure
 // pattern that future shrinks should follow. Byte counts noted for reference.
 const XL_WORKFLOWS = new Set([
-  'execute-phase',  // 92525 bytes (tier high-water mark; grew in #913 inline-fallback scope clarification)
-  'plan-phase',     // 90748 bytes (grew in #922 attempt-based Agent gate)
-  'new-project',    // 55850 bytes
+  'execute-phase',  // 92880 bytes (grew in #381 CLAUDE_ENV_FILE persist clause)
+  'plan-phase',     // 93130 bytes (tier high-water mark; grew in #381 CLAUDE_ENV_FILE persist clause)
+  'new-project',    // 61685 bytes
 ]);
 
 // Multi-step planners and bigger feature workflows. Grandfathered.