Release v4.2.9: Progressive disclosure experimental feature announcement

Documentation Updates:
- Added experimental progressive disclosure context system section to README
- Created EXPERIMENTAL_RELEASE_NOTES.md with comprehensive testing guide
- Created GITHUB_RELEASE_TEMPLATE.md for release announcements
- Updated all version references to 4.2.9 (package.json, marketplace.json, CLAUDE.md, README.md)

Progressive Disclosure Concept:
- Layer 1: Index showing what observations exist with token costs
- Layer 2: On-demand details via MCP search
- Layer 3: Perfect recall via source code access

Purpose:
- Invite users to test feature/context-with-observations branch
- Gather feedback on observation-level context vs summary-only approach
- Validate whether token cost metadata improves Claude's retrieval decisions

Testing Instructions:
- Clear documentation on how to clone, build, and test experimental branch
- Feedback template provided for structured user responses
- GitHub issues encouraged with label 'feedback: progressive-disclosure'

Files Changed:
- README.md (experimental feature section)
- EXPERIMENTAL_RELEASE_NOTES.md (new)
- GITHUB_RELEASE_TEMPLATE.md (new)
- package.json (version bump)
- .claude-plugin/marketplace.json (version bump)
- CLAUDE.md (version history + version number)
- plugin/scripts/*.js (rebuilt)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

GITHUB_RELEASE_TEMPLATE.md

@@ -0,0 +1,83 @@
+# 🧪 Experimental: Progressive Disclosure Context System
+
+> **We'd love your feedback!** Test the new context injection approach and share your experience.
+
+## What is Progressive Disclosure?
+
+A **layered memory retrieval system** that shows Claude:
+1. **Index** (frontloaded): What observations exist + token costs
+2. **Details** (on-demand): Full narratives via MCP search
+3. **Perfect recall**: Source code when needed
+
+**The idea:** Instead of hiding observations completely, show an index so Claude can make informed decisions about what to fetch.
+
+## Try It Out
+
+```bash
+# Clone and build experimental version
+git clone https://github.com/thedotmack/claude-mem.git
+cd claude-mem
+git checkout feature/context-with-observations
+npm install && npm run build
+
+# Navigate to YOUR project and run the hook
+cd /path/to/your/project
+node /path/to/claude-mem/plugin/scripts/context-hook.js
+```
+
+**Important:** Run from your project's root directory to see context for that project.
+
+## What's Different?
+
+**Current (v4.2.x):** Session summaries only (~800 tokens)
+```markdown
+Session #312: Put date/time at end of session titles
+Completed: Added formatting
+Next: Test edge cases
+```
+
+**Experimental:** Observation index + summaries (~2,500 tokens)
+```markdown
+**src/hooks/context.ts**
+| ID | Time | T | Title | Tokens |
+|----|------|---|-------|--------|
+| #2332 | 1:07 AM | 🔴 | Critical Bugfix: Session ID NULL | ~201 |
+| #2340 | 1:10 AM | 🟠 | Remove Redundant Summary Section | ~280 |
+```
+
+Now Claude knows:
+- What learnings exist (without loading them)
+- Cost to fetch details (~200 tokens)
+- Priority (🔴 critical vs 🔵 informational)
+
+## We Want Your Feedback
+
+Test the experimental branch and tell us:
+
+✅ **Does Claude use MCP search more effectively?**
+💰 **Do token counts influence retrieval decisions?**
+📖 **Are the instructions helpful or noisy?**
+🚀 **Does it reduce redundant code reading?**
+
+### 📣 [Please Open a GitHub Issue](https://github.com/thedotmack/claude-mem/issues/new) With Your Experience!
+
+Use the label `feedback: progressive-disclosure` - all feedback is valuable, positive or negative!
+
+## Files Changed
+
+- Updated `README.md` with experimental feature section
+- Enhanced `src/hooks/context.ts` with progressive disclosure instructions
+- New docs: `EXPERIMENTAL_RELEASE_NOTES.md` (full details)
+
+## Next Steps
+
+Based on your feedback:
+- ✅ **If successful:** Merge to main, release as v4.3.0
+- ⚠️ **If mixed:** Make opt-in via settings
+- ❌ **If unsuccessful:** Keep iterating as experimental
+
+---
+
+**Full details:** See [EXPERIMENTAL_RELEASE_NOTES.md](EXPERIMENTAL_RELEASE_NOTES.md)
+
+**Questions?** Join the discussion or open an issue!