Adding context-os under Developer Productivity.

What it is: a stdlib-Python Claude Code plugin (MIT) that gives Claude a static-analysis repo graph (symbols + line ranges + imports + git-hot files) injected pre-prompt, so the first turn opens the right file instead of grepping for it. Plus PreToolUse hooks (smart_read, smart_bash) that intercept whole-file Reads — and pure cat/less dumps via Bash — and hand Claude the file's structural outline so it reads only the slice it needs. Plus /savings Receipts that measure both sources causally from the transcript.

Why distinct from existing entries:

• vs context-mode: that processes large tool outputs in subprocesses to keep summaries in context; context-os attacks earlier — which file Claude opens first + whether a whole-file dump enters context at all.
• vs codebase-graph: that's an MCP server with tree-sitter + FalkorDB; context-os is a stdlib-only hook (no MCP server, no DB, no embeddings), trading some recall for zero-deps + ~50ms hook latency.

Honest evidence (CI-gated, reproducible):

• Retrieval quality: MRR 0.984 on synthetic Py/TS/Rust, beats BM25 in every language across 3 unseen OSS repos (axios / ripgrep / requests).
• claude --print A/B: −40.9% aggregate tokens (N=36, p=5e-7) — cold-cache one-shots; in a warm interactive session the dollar delta is smaller due to caching, so the durable win is fewer first-turn tool calls + later compaction.
• ~100 assertions in CI cover the hook pipeline including adversarial Bash-parser pass-throughs (pipes, redirects, chains, substitutions must never false-positive-block).
• Anyone can validate on their own Claude Code history (no API key): python3 python/evals/runners/replay_history.py.

The plugin passes the contributing checks: addresses a real use case (first-turn exploration + compounding context bloat), doesn't duplicate the existing entries (different mechanism), follows the plugin structure (.claude-plugin/plugin.json, commands/, etc.), tested (CI badge green).

Happy to adjust the description length or category if you'd prefer it elsewhere.