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>

README.md

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 ---
 
+## 🧪 Experimental Feature: Progressive Disclosure Context
+
+> **We'd love your feedback!** Test the new context injection system in `feature/context-with-observations`
+
+### What is Progressive Disclosure?
+
+Progressive disclosure is a layered approach to memory retrieval that mirrors how humans remember information:
+
+**Layer 1: Index** (Frontloaded at session start)
+- **WHAT** exists: Observation titles and session summaries
+- **COST** of retrieval: Token counts for each observation
+- **TYPE** indicators: Critical (🔴 gotcha, 🟤 decision) vs informational (🔵 how-it-works)
+
+**Layer 2: Details** (Retrieved on-demand via MCP search)
+- Full observation narratives when Claude needs deeper context
+- Search by concept, file, type, or keyword
+
+**Layer 3: Perfect Recall** (Code/transcripts)
+- Source code when implementation details are needed
+- Original transcripts for exact quotes
+
+### The Problem It Solves
+
+**Current version** (v4.2.x): Shows only session-level summaries at startup
+- ✅ Minimal tokens (~800)
+- ❌ Claude doesn't know what detailed observations exist
+- ❌ Often re-reads code to understand past decisions
+
+**Experimental version**: Shows observation index + session summaries
+- ✅ Claude sees WHAT learnings exist without loading full content
+- ✅ Token counts help Claude decide: "fetch details" vs "read code"
+- ✅ Progressive disclosure instructions teach Claude how to use the system
+- ⚠️ Higher token cost (~2,500) but potentially more efficient overall
+
+### How It's Different
+
+The experimental context hook displays observations in a **table format**:
+
+```markdown
+**src/hooks/context.ts**
+| ID | Time | T | Title | Tokens |
+|----|------|---|-------|--------|
+| #2332 | 1:07 AM | 🔴 | Critical Bugfix: Session ID NULL Constraint | ~201 |
+| #2340 | 1:10 AM | 🟠 | Remove Redundant Summary Section | ~280 |
+```
+
+Now Claude knows:
+- A critical bugfix exists about session IDs (~201 tokens to fetch)
+- A design decision exists about summary sections (~280 tokens)
+- Whether to use MCP search or just read the current code
+
+### Try It Out
+
+```bash
+# Clone and checkout the experimental branch
+git clone https://github.com/thedotmack/claude-mem.git
+cd claude-mem
+git checkout feature/context-with-observations
+
+# Build the experimental version
+npm install
+npm run build
+
+# Test the new context hook (from YOUR project directory)
+cd /path/to/your/project
+node /path/to/claude-mem/plugin/scripts/context-hook.js
+
+# Example:
+# cd ~/my-app
+# node ~/claude-mem/plugin/scripts/context-hook.js
+```
+
+**Important:** Run the context hook from your project's root directory to see context specific to that project.
+
+**We want to know:**
+- Does Claude use MCP search more effectively?
+- Do token counts influence retrieval decisions?
+- Is the progressive disclosure guidance helpful or noisy?
+- Does it reduce redundant code reading?
+
+**📣 Share Your Feedback:** [Open a GitHub Issue](https://github.com/thedotmack/claude-mem/issues/new) with your experience! Tag it with `feedback: progressive-disclosure`
+
+---
+
 ## Quick Start
 
 Start a new Claude Code session in the terminal and enter the following commands: