gstack: artifacts auto-sync silently broken due to unexpanded ~ in double-quoted bash variable assignments #1715

Bug: Bash tilde expansion fails inside double-quoted variable assignments in gstack skill preamble, preventing artifacts auto-sync on all skill invocations

Description

On Windows (Git Bash), the gstack skill preamble's artifacts sync logic silently never runs. The ~ in double-quoted variable assignments is not resolved to the home directory path.

This means gstack-brain-sync --once is never called at skill boundaries, so cross-machine artifact synchronization (checkpoints, learnings, timeline, etc.) does not happen automatically.

Root Cause

In Bash, tilde expansion only occurs when ~ is at the beginning of an unquoted word. Inside double-quoted variable assignments, ~ is treated as a literal character.

Lines 369-370 in every SKILL.md preamble:

_BRAIN_SYNC_BIN="~/.claude/skills/gstack/bin/gstack-brain-sync"
_BRAIN_CONFIG_BIN="~/.claude/skills/gstack/bin/gstack-config"

When $_BRAIN_CONFIG_BIN is later invoked:

_BRAIN_SYNC_MODE=$("$_BRAIN_CONFIG_BIN" get artifacts_sync_mode 2>/dev/null || echo off)

The shell tries to execute the literal path ~/.claude/... (which doesn't exist as a literal file path), the command fails, and artifacts_sync_mode falls back to off. This causes all subsequent sync conditions to evaluate to false.

The same issue affects the end-of-skill sync commands in the Telemetry section:

"~/.claude/skills/gstack/bin/gstack-brain-sync" --once 2>/dev/null || true

Impact

• Every gstack skill invocation (/context-save, /qa, /ship, /plan-*, /review, etc.) silently skips the artifacts sync
• Cross-machine artifact sharing via the gstack artifacts git repo (gstack-record) never works automatically
• No user-visible error — all || true / 2>/dev/null patterns swallow the failure silently
• This has been broken since the artifacts sync feature was introduced

Affected Files

All 92 SKILL.md files across two directories:

• ~/.claude/skills/*/SKILL.md (46 files — loaded by Claude Code at runtime)
• ~/.claude/skills/gstack/*/SKILL.md (46 files — gstack distribution copies)

Affected skills include: autoplan, benchmark, benchmark-models, browse, canary, codex, context-restore, context-save, cso, design-consultation, design-html, design-review, design-shotgun, devex-review, document-generate, document-release, health, investigate, ios-clean, ios-design-review, ios-fix, ios-qa, ios-sync, land-and-deploy, landing-report, learn, make-pdf, office-hours, open-gstack-browser, pair-agent, plan-ceo-review, plan-design-review, plan-devex-review, plan-eng-review, plan-tune, qa, qa-only, retro, review, scrape, setup-browser-cookies, setup-deploy, setup-gbrain, ship, skillify, sync-gbrain

Fix

Change "~/.claude/..." to "$HOME/.claude/..." in two places in the preamble template and the end-of-skill telemetry section.

In the Artifacts Sync preamble section:

- _BRAIN_SYNC_BIN="~/.claude/skills/gstack/bin/gstack-brain-sync"
- _BRAIN_CONFIG_BIN="~/.claude/skills/gstack/bin/gstack-config"
+ _BRAIN_SYNC_BIN="$HOME/.claude/skills/gstack/bin/gstack-brain-sync"
+ _BRAIN_CONFIG_BIN="$HOME/.claude/skills/gstack/bin/gstack-config"

In the end-of-skill Telemetry section:

- "~/.claude/skills/gstack/bin/gstack-brain-sync" --once 2>/dev/null || true
+ "$HOME/.claude/skills/gstack/bin/gstack-brain-sync" --once 2>/dev/null || true

Verification

After fixing, the preamble correctly shows ARTIFACTS_SYNC: mode=full | ... instead of ARTIFACTS_SYNC: off. Git status on ~/.gstack/ confirms that gstack-brain-sync --once modified learnings.jsonl, timeline.jsonl, and .brain-queue.jsonl.

Environment

• OS: Windows 11 (Git Bash)
• Shell: Bash (via Git for Windows)