docs: write substantive README.md

README.md

@@ -1,19 +1,60 @@
 # molecule-session-context
 
-Molecule AI plugin. Install via the Molecule AI platform plugin system.
+Auto-loads recent learnings and workspace activity at session start. Pairs with `molecule-skill-cron-learnings` — together they give the agent a running summary of past decisions and current state before beginning work.
 
-## Usage
+## What it loads
+
+1. **Recent learnings** — reads the last 10 entries from `~/.molecule/cron-learnings.jsonl` (written by `molecule-skill-cron-learnings`)
+2. **Repo activity** — runs `git log --oneline -10` to surface recent commits
+3. **Issue counts** — runs `gh issue list --state open` to show open items
+
+All output is emitted as `additionalContext` on `SessionStart`.
+
+## Install
 
 ### In org template (org.yaml)
+
 ```yaml
 plugins:
   - molecule-session-context
 ```
 
+**Recommended:** Also install `molecule-skill-cron-learnings` to populate the learnings file.
+
 ### From URL (community install)
+
 ```
 github://Molecule-AI/molecule-ai-plugin-molecule-session-context
 ```
 
+## Usage
+
+No configuration needed. Install to activate — the hook fires on every session start.
+
+## Hooks
+
+- **SessionStart** — reads learnings + git log + issue counts, emits as context
+
+## Architecture
+
+```
+hooks/
+  session-start-context.py   # Reads learnings, git, gh; emits additionalContext
+  session-start-context.sh   # Shell wrapper
+  _lib.py                     # Shared helpers
+adapters/
+  claude_code.py              # Registers hook
+settings-fragment.json        # Declares SessionStart hook binding
+```
+
+## Runtime
+
+- `claude_code` — primary
+
+## Known issues
+
+See [known-issues.md](known-issues.md).
+
 ## License
+
 Business Source License 1.1 — © Molecule AI.