feat(12-01): create CHANGELOG.md with Keep-a-Changelog format

- Added 1.4.24 entry documenting parallel execution, planning changes
- Marked ISSUES.md removal as BREAKING change
- Established changelog structure for ongoing releases

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.planning/ROADMAP.md

@@ -19,6 +19,7 @@ None - this is internal GSD development following existing command/workflow/temp
 - [ ] **Phase 3: Integration** - Wire brownfield support into existing GSD workflows
 - [x] **Phase 10: Parallel Phase Execution** - Separate single-plan vs multi-plan execution with intelligent parallelization
 - [x] **Phase 11: Parallel-Aware Planning** - Update plan-phase.md to create parallelizable plans when config enables it
+- [ ] **Phase 12: Changelog & Update Awareness** - Add changelog generation and /gsd:whats-new for version discovery
 - [x] **Phase 99: Test Parallel (THROWAWAY)** - Create 3 silly independent files to test parallel execution
 
 ## Phase Details
@@ -191,6 +192,25 @@ Current plan-phase.md has sequential execution bias - later plans reference earl
 
 This enables execute-phase to produce more Wave 1 plans (true independence) instead of sequential chains.
 
+### Phase 12: Changelog & Update Awareness
+
+**Goal:** Add changelog generation to publish workflow and `/gsd:whats-new` command for users to discover changes
+**Depends on:** Phase 11
+**Research:** Unlikely (straightforward command + workflow additions)
+**Plans:** 3 plans
+
+Plans:
+- [ ] 12-01: CHANGELOG.md foundation - Create changelog file, update installer to copy it
+- [ ] 12-02: Publish command update - Add changelog generation to gsd-publish-version.md
+- [ ] 12-03: whats-new command - Create /gsd:whats-new with remote fetch and version comparison
+
+**Wave structure:**
+- Wave 1: 12-01 (foundation)
+- Wave 2: 12-02, 12-03 (parallel - both depend only on 12-01)
+
+**Details:**
+Users adopting GSD need visibility into what changed between versions. The publish workflow generates curated changelog entries (Claude-drafted, Lex-approved). `/gsd:whats-new` fetches from GitHub raw, compares to installed version, and prompts to update if behind.
+
 ### Phase 99: Test Parallel (THROWAWAY)
 
 **Goal:** Create 3 independent silly files to test parallel execution - DELETE AFTER TESTING

CHANGELOG.md

@@ -0,0 +1,24 @@
+# Changelog
+
+All notable changes to GSD will be documented in this file.
+
+Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## [Unreleased]
+
+## [1.4.24] - 2026-01-14
+
+### Added
+- Parallel phase execution via `/gsd:execute-phase`
+- Parallel-aware planning in `/gsd:plan-phase`
+- Changelog and update awareness system
+
+### Changed
+- Renamed `execute-phase.md` workflow to `execute-plan.md` for clarity
+- Plan frontmatter now includes `wave`, `depends_on`, `files_modified`, `autonomous`
+
+### Removed
+- **BREAKING:** ISSUES.md system (replaced by phase-scoped UAT issues and TODOs)
+
+[Unreleased]: https://github.com/glittercowboy/get-shit-done/compare/v1.4.24...HEAD
+[1.4.24]: https://github.com/glittercowboy/get-shit-done/releases/tag/v1.4.24