feat: Factory Droid compatibility — works across Claude Code, Codex, and Factory (v0.13.5.0) (#621)

* refactor: extract processExternalHost() shared helper for multi-host generation

Refactor the Codex-specific output routing block in gen-skill-docs.ts into
a shared processExternalHost() function. Both Codex and future external hosts
(Factory Droid) will use this helper for output routing, symlink loop detection,
frontmatter transformation, path rewrites, and metadata generation.

- Rename codexSkillName() to externalSkillName() everywhere
- Extract ExternalHostConfig interface with per-host settings
- Codex output is byte-identical (verified via --dry-run)
- Skip /codex skill for all non-Claude hosts (not just codex)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add Factory Droid host type, preamble, and co-author trailer

- Add 'factory' to Host union type with .factory/skills/gstack paths
- Extend preamble runtime root detection for Factory ($HOME/.factory/)
- Add GSTACK_DESIGN env var to preamble (was missing for Codex too)
- Add Factory Droid co-author trailer for git commits

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: Factory Droid generation, --host all, and host-aware frontmatter

- Add --host factory (alias: --host droid) to gen-skill-docs
- Add --host all: generates for claude, codex, and factory in one invocation
  with fault-tolerant per-host error handling (only fails if claude fails)
- Factory frontmatter: name + description + user-invocable: true
- Factory sensitive skills: disable-model-invocation: true (from sensitive: field)
- Claude: strips sensitive: field from output (only Factory uses it)
- Factory tool name translation: Claude tool names → generic phrasing
- Replace chained gen:skill-docs calls with --host all in package.json build

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: sensitive frontmatter for Factory Droid auto-invocation safety

Add sensitive: true to 6 skill templates with side effects that Factory
Droids shouldn't auto-invoke (ship, land-and-deploy, guard, careful,
freeze, unfreeze). The field is:
- Factory: emitted as disable-model-invocation: true
- Claude/Codex: stripped from output by transformFrontmatter()

Also fix Claude host path: call transformFrontmatter() for Claude to
strip the sensitive: field from Claude output.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: gstack-platform-detect binary for multi-host debugging

Bash script that prints a table of installed AI coding agents (Claude,
Codex, Factory Droid, Kiro) with versions, skill paths, and gstack
installation status. Useful for debugging multi-host setups.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: Factory Droid support in setup script

- Add factory to --host values (auto-detected via command -v droid)
- Add .factory/ skill doc generation step alongside .agents/
- Add create_factory_runtime_root() and link_factory_skill_dirs()
  helpers mirroring the Codex equivalents
- Factory install section creates ~/.factory/skills/ with symlinks

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: Factory Droid awareness in skill-check and uninstall

- skill-check.ts: add Factory skills validation and freshness check
- gstack-uninstall: add Factory artifact cleanup (~/.factory/skills/gstack*
  and per-project .factory/ sidecar)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test: Factory Droid generation + --host all test suites

Add 13 new tests:
- Factory output paths, frontmatter (user-invocable, disable-model-invocation)
- Sensitive vs non-sensitive skill classification
- Path rewrites (no .claude/skills/ in Factory output)
- /codex skill exclusion, openai.yaml absence
- Factory keeps Codex integration blocks (for second opinions)
- --host droid alias, --dry-run freshness, preamble paths
- --host all generates for all 3 hosts
- Setup script host validation updated for factory

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: Factory Droid install instructions + CI freshness check

- README: add Factory Droid section with install instructions and
  restart note (Factory requires restart to rescan skills)
- CI: add Factory skill doc freshness verification to skill-docs.yml

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: generated Factory Droid skill output (.factory/skills/)

29 skills generated for Factory Droid with:
- user-invocable: true on all skills
- disable-model-invocation: true on 6 sensitive skills
- .factory/skills/ paths (no .claude/skills/ references)
- $GSTACK_ROOT env vars for runtime root detection
- Tool name translation (Claude tool names → generic phrasing)

Committed to git for CI freshness checks and direct consumption.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: add Factory Droid P1 TODO for browse MCP server

Add 3 TODOs under new ## Factory Droid section:
- P1: Browse MCP server (Option B, deeper Factory integration)
- P3: .agent/skills/ dual output for cross-agent compatibility
- P3: Custom Droid definitions alongside skills

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v0.13.5.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.factory/skills/gstack-guard/SKILL.md

@@ -0,0 +1,64 @@
+---
+name: guard
+description: |
+  Full safety mode: destructive command warnings + directory-scoped edits.
+  Combines /careful (warns before rm -rf, DROP TABLE, force-push, etc.) with
+  /freeze (blocks edits outside a specified directory). Use for maximum safety
+  when touching prod or debugging live systems. Use when asked to "guard mode",
+  "full safety", "lock it down", or "maximum safety".
+user-invocable: true
+disable-model-invocation: true
+---
+<!-- AUTO-GENERATED from SKILL.md.tmpl — do not edit directly -->
+<!-- Regenerate: bun run gen:skill-docs -->
+> **Safety Advisory:** This skill includes safety checks that check bash commands for destructive operations (rm -rf, DROP TABLE, force-push, git reset --hard, etc.) before execution, and verify file edits are within the allowed scope boundary before applying, and verify file writes are within the allowed scope boundary before applying. When using this skill, always pause and verify before executing potentially destructive operations. If uncertain about a command's safety, ask the user for confirmation before proceeding.
+
+
+# /guard — Full Safety Mode
+
+Activates both destructive command warnings and directory-scoped edit restrictions.
+This is the combination of `/careful` + `/freeze` in a single command.
+
+**Dependency note:** This skill references hook scripts from the sibling `/careful`
+and `/freeze` skill directories. Both must be installed (they are installed together
+by the gstack setup script).
+
+```bash
+mkdir -p ~/.gstack/analytics
+echo '{"skill":"guard","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true
+```
+
+## Setup
+
+Ask the user which directory to restrict edits to. Use AskUserQuestion:
+
+- Question: "Guard mode: which directory should edits be restricted to? Destructive command warnings are always on. Files outside the chosen path will be blocked from editing."
+- Text input (not multiple choice) — the user types a path.
+
+Once the user provides a directory path:
+
+1. Resolve it to an absolute path:
+```bash
+FREEZE_DIR=$(cd "<user-provided-path>" 2>/dev/null && pwd)
+echo "$FREEZE_DIR"
+```
+
+2. Ensure trailing slash and save to the freeze state file:
+```bash
+FREEZE_DIR="${FREEZE_DIR%/}/"
+STATE_DIR="${CLAUDE_PLUGIN_DATA:-$HOME/.gstack}"
+mkdir -p "$STATE_DIR"
+echo "$FREEZE_DIR" > "$STATE_DIR/freeze-dir.txt"
+echo "Freeze boundary set: $FREEZE_DIR"
+```
+
+Tell the user:
+- "**Guard mode active.** Two protections are now running:"
+- "1. **Destructive command warnings** — rm -rf, DROP TABLE, force-push, etc. will warn before executing (you can override)"
+- "2. **Edit boundary** — file edits restricted to `<path>/`. Edits outside this directory are blocked."
+- "To remove the edit boundary, run `/unfreeze`. To deactivate everything, end the session."
+
+## What's protected
+
+See `/careful` for the full list of destructive command patterns and safe exceptions.
+See `/freeze` for how edit boundary enforcement works.