fix(host-paths): use $HOME instead of ~ in non-env-var host paths

[jisulee42]

Summary

HOST_PATHS for Claude (and any future non-env-var host) emits paths
starting with a literal ~. Several preamble blocks then interpolate
those paths inside double quotes (e.g. generate-brain-sync-block.ts:45
emits _BRAIN_SYNC_BIN="${ctx.paths.binDir}/gstack-brain-sync").
POSIX shells do not expand ~ inside double quotes, so the emitted
line is a literal "~/.claude/.../gstack-brain-sync" and every call to
that binary fails with exit 127, No such file or directory. Both
stderr and the exit code are swallowed by 2>/dev/null || true, so
the failure is silent.

Practical impact: on every Claude Code install with artifacts_sync_mode
on, the skill preambles call gstack-brain-sync --once on every skill
boundary, but the binary is never reached. The artifacts queue
(~/.gstack/.brain-queue.jsonl) grows indefinitely while
~/.gstack/.brain-last-push stays at never. I hit this exact symptom
locally after running /setup-gbrain — ~24 hours of skill usage, queue
at 45 entries, last-push never, status file never created. Manual
gstack-brain-sync --once drained the queue and pushed cleanly, which
confirmed the binary itself works and the problem was upstream of the
call.

codex and factory hosts are unaffected: they use $GSTACK_BIN,
which DOES expand inside double quotes.

Root cause

scripts/resolvers/types.ts:37 (before):

} else {
  const root = `~/${config.globalRoot}`;   // literal ~
  paths[config.name] = {
    skillRoot: root,
    binDir: `${root}/bin`,
    ...
  };
}

The emitter at scripts/resolvers/preamble/generate-brain-sync-block.ts:45
then wraps that value in double quotes, defeating tilde expansion.

Fix

One-line: emit $HOME/${config.globalRoot} instead of ~/${config.globalRoot}.
Same semantics outside quotes (both expand), correct semantics inside
quotes (only $HOME expands). Added a WHY comment pointing at bash(1)
"Tilde Expansion" + "Parameter Expansion" so the next person who looks
at this knows why it matters.

Why CI didn't catch it

Two reasons, both worth fixing:

1. test/host-config.test.ts:246 asserted the broken form as the
   expected value:

   expect(HOST_PATHS.claude.binDir).toBe('~/.claude/skills/gstack/bin');

   The test was passing because the code produced the same broken value
   the test was asserting. Updated to expect $HOME/....

2. test/fixtures/golden/claude-ship-SKILL.md was generated from
   the broken code path, so golden-file regression was comparing the
   bug against itself. Regenerated via bun run gen:skill-docs --host all.

Also added a narrow regression guard at
test/host-config.test.ts (HOST_PATHS describe block):

test('non-env-var binDirs are safe to interpolate inside double quotes (no leading ~)', () => {
  for (const config of ALL_HOST_CONFIGS) {
    if (!config.usesEnvVars) {
      expect(HOST_PATHS[config.name].binDir.startsWith('~')).toBe(false);
      // ... + skillRoot/browseDir/designDir/makePdfDir
    }
  }
});

If anyone reintroduces the literal-tilde form later, this fires
immediately.

Diff shape

• scripts/resolvers/types.ts — +6 / -1 (one-line fix + WHY comment).
• test/host-config.test.ts — +20 / -8 (assertion updates + regression
  guard).
• test/fixtures/golden/claude-ship-SKILL.md — +57 / -57 (golden
  regen, ~ → $HOME).
• 42 Claude-host */SKILL.md files — auto-regenerated via
  bun run gen:skill-docs --host all. Codex/Factory artifacts
  unchanged.

The 42 SKILL.md files dominate the diff line count but are mechanical
regen output. Reviewer focus: scripts/resolvers/types.ts (6 lines)
and test/host-config.test.ts (~30 lines).

Test plan

• bun test test/host-config.test.ts — 74 pass, 0 fail (includes
  new regression guard).
• bun test test/gen-skill-docs.test.ts test/brain-sync.test.ts —
  412 pass, 0 fail.
• bun test test/preamble-compose.test.ts test/gstack-gbrain-sync.test.ts test/gbrain-sources.test.ts —
  34 pass, 0 fail.
• bun run test (main suite, e2e excluded) — green locally.
• Manual verification of the original symptom: gstack-brain-sync --once
  now reachable, queue drains, push succeeds, ~/.gstack/.brain-last-push
  updates.

Notes for maintainer

I found this while debugging "/sync-gbrain isn't actually pushing
anything" on a fresh /setup-gbrain install. Happy to split into
two PRs (fix vs. regenerated artifacts) if you'd prefer the diff
to land more narrowly, but the regen is verbatim output of
bun run gen:skill-docs --host all against the one-line fix and
should be deterministic. Searched open issues/PRs for prior reports
of this — none found.

🤖 Generated with Claude Code

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