docs(12-03): complete whats-new command plan

Tasks completed: 3/3
- Create whats-new.md command
- Update install.js to write VERSION file
- Update help.md to include whats-new command

SUMMARY: .planning/phases/12-changelog-and-update-awareness/12-03-SUMMARY.md

.planning/phases/12-changelog-and-update-awareness/12-03-SUMMARY.md

@@ -0,0 +1,87 @@
+---
+phase: 12-changelog-and-update-awareness
+plan: 03
+subsystem: infra
+tags: [changelog, version, whats-new, update-awareness]
+
+requires:
+  - phase: 12-01
+    provides: CHANGELOG.md file and installer changelog copy
+provides:
+  - /gsd:whats-new command for version comparison
+  - VERSION file written during installation
+  - Help documentation for whats-new command
+affects: []
+
+tech-stack:
+  added: []
+  patterns:
+    - Remote changelog fetch via WebFetch for update awareness
+    - VERSION file for installed version tracking
+
+key-files:
+  created:
+    - commands/gsd/whats-new.md
+  modified:
+    - bin/install.js
+    - commands/gsd/help.md
+
+key-decisions:
+  - "VERSION file approach (simpler than parsing package.json)"
+  - "Remote fetch from GitHub raw for discovering unreleased changes"
+  - "Graceful fallback to local changelog when offline"
+
+duration: 4min
+completed: 2026-01-14
+---
+
+# Phase 12 Plan 03: whats-new Command Summary
+
+**/gsd:whats-new command created for users to discover changes since their installed version, with VERSION file written during installation and help documentation updated**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-01-14T20:10:00Z
+- **Completed:** 2026-01-14T20:14:00Z
+- **Tasks:** 3
+- **Files modified:** 3
+
+## Accomplishments
+- Created /gsd:whats-new command with remote changelog fetch
+- Added VERSION file creation to installer
+- Updated help.md with whats-new command documentation
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Create whats-new.md command** - `1a55ac8` (feat)
+2. **Task 2: Update install.js to write VERSION file** - `b281148` (feat)
+3. **Task 3: Update help.md to include whats-new command** - `68f3cd1` (docs)
+
+## Files Created/Modified
+- `commands/gsd/whats-new.md` - Command for version comparison and changelog display
+- `bin/install.js` - Added VERSION file creation during installation
+- `commands/gsd/help.md` - Added whats-new to Utility Commands section
+
+## Decisions Made
+- VERSION file approach chosen over parsing package.json (simpler, more reliable)
+- Remote fetch from GitHub enables discovering changes in versions not yet installed
+- Graceful fallback to local changelog when offline or GitHub unavailable
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## Next Phase Readiness
+- /gsd:whats-new command ready for users to discover updates
+- Phase 12 complete (all 3 plans finished)
+- Ready for phase completion and milestone wrap-up
+
+---
+*Phase: 12-changelog-and-update-awareness*
+*Completed: 2026-01-14*