Mogestrator

A local code knowledge graph for coding agents. Mogestrator indexes a repository, retrieves scoped context, and detects when anchored code or remembered facts have changed. Code stays local; no account or API key is required.

Status: 0.1.2 is the stable indexing release. 0.2.0a3 includes M1 indexing, memory freshness fixes, and experimental retrieval and MCP integration. The broader M2 quality gate remains open: there is no evidence yet that this beats ripgrep or chunk RAG on real development tasks.

Install and try

Python 3.11+:

pip install --pre "mogestrator[mcp]==0.2.0a3"
mog init
mog index
mog search "verify_token" --explain
mog verify

Or install this checkout:

uv venv
uv pip install -e ".[mcp]"
source .venv/bin/activate

Version 0.0.1 was a name-only placeholder. Check PyPI for available versions. Other distribution channels (Homebrew, standalone binaries, Docker, npm) remain planned.

What works

Retrieval and inspection

mog index [--full]
mog status [--secrets]
mog verify [--strict]
mog show src/auth.py::verify_token
mog map

mog search "where are refresh tokens validated" --budget 4000 --explain
mog search verify_token --kind symbol --json
mog expand src/auth.py::verify_token --zoom L2
mog impact verify_token --depth 2 --tests
mog neighbors verify_token --edge calls --reverse

All commands above take --repo PATH. index, status, verify, and retrieval commands support --json. Path-qualified lookups must match the file; ambiguous retrieval targets require a path or node ID.

Search combines exact/FTS ranks with bounded bidirectional graph spread. Every result includes an anchor, current freshness, trust labels, and a provenance path. Graph traversal is capped; call resolution is a name-based heuristic, not a complete static analyzer. Local imports links and Git-derived co_changed edges are conservative ranking hints.

Zoom levels: L0 summarizes the node's file; L1 shows signatures; L2 reads a symbol body; L3 reads the full file. Automatic zoom falls back to signatures for large hits so related results can fit the budget. Blame/diff augmentation is not implemented. Source views are reparsed, so edits above a symbol cannot make stored offsets return the wrong body. If a source changed, current content is labelled stale relative to the stored anchor. Missing or out-of-tree source bodies are not returned.

The context budget includes the compact JSON payload and metadata. Accounting uses a conservative UTF-8 byte upper bound for byte-level tokenizers, not an exact model-specific token count. Large bodies are explicitly truncated; items whose metadata cannot fit are omitted. MCP transport wrappers and client formatting are outside this budget.

Optional local semantic search

pip install --pre "mogestrator[embeddings]==0.2.0a3"
mog index
mog embed                      # first run downloads BAAI/bge-small-en-v1.5
mog search "validate a user's login credentials" --semantic

Inference is local. Model weights are cached in the platform's Mogestrator cache; MOG_MODEL_CACHE can override the directory. Embeddings are cached in SQLite by model and content hash. Run mog embed again after indexing changes; watch mode updates the graph, not embeddings. Without a semantic index, the search explicitly falls back to FTS and graph retrieval. Vector ranking currently scans the cached vectors; large-repository k-NN indexing remains future work.

Memory

mog remember decision "Use local validation to avoid a network dependency" --anchor verify_token
mog why "local validation"
mog recall deci_ID --json
mog pin deci_ID
mog unpin deci_ID

Memories survive re-indexing and process restarts. Anchored facts retain their original hashes on body edits, so editing a source marks them stale instead of silently rewriting history. Unique renames move the anchor but mark the memory stale with a review warning: its text may still name the old symbol or path. The original anchor is retained in metadata. After review, record a new memory against the current symbol; re-indexing never validates the old wording. Moves processed by older versions did not retain the original anchor and need manual memory review; this fix cannot identify them retroactively. Unanchored memories have no source drift check. recall returns the original recorded content. Pinning is persisted for ranking and future working-set management; automatic eviction, recall stubs, conflict resolution, and conversation capture are not implemented.

MCP integration

Start the stdio server for a fixed repository:

mog serve --mcp --repo /absolute/path/to/repo --watch

Use this command as the server executable in an MCP client. For example, a client configuration entry can launch:

{
  "mcpServers": {
    "mog": {
      "command": "mog",
      "args": ["serve", "--mcp", "--repo", "/absolute/path/to/repo", "--watch"]
    }
  }
}

--watch creates an initial index and polls for changes every second. Protocol stdout stays clean; diagnostics go to stderr. For Streamable HTTP:

mog serve --mcp --transport http --port 8765 --repo /absolute/path/to/repo --watch
# endpoint: http://127.0.0.1:8765/mcp

HTTP binds only to loopback; remote authenticated/multi-user hosting is not part of this release.

Use Mogestrator selectively. Search when relevant code is unknown, expand only when a snippet is insufficient, and use why when a prior decision or failure matters to the task. Retrieval checks the returned items' freshness already; reserve verify for explicit drift audits. There is no required session-start index/verify/why sequence. With --watch, indexing refreshes automatically. An empty memory lookup returns without reading source files or traversing the graph. Remember durable decisions, failures, and handoffs rather than each action.

Tools: search_context, expand, impact, neighbors, why, remember, recall, pin, unpin, verify, create_context, load_context. create_context saves a query plus optional pinned references as a ctx:// handle; another client can materialize it against the current index with load_context. Source references survive ordinary re-indexing.

Writes are opt-in: add --allow-memory-writes to enable remember, pin/unpin, and context-handle creation. Agent-origin writes may create decisions, failures, and tasks; they cannot create higher-trust corrections or constraints. All returned repository and memory content is untrusted data. Labels are useful provenance, not a complete prompt-injection defense; the policy gateway remains planned. Credential detection is heuristic, not a guarantee of detecting every secret.

Agent-session evaluation

Claude Code — 2026-09-30

Mogestrator was tested against plain Claude Code on a private Python project (~1.7k LOC; name and code withheld). Each prompt ran as a headless Claude Code session in an OS sandbox, and hidden acceptance checks the agents never saw scored the work. Total spend was $68.

Exp A covers a long task sequence: 4 runs per arm, 10 prompts, 3 sessions, with 2 teammate commits between sessions.

Exp B tests stale notes: 3 runs per cell. Seven notes from a "previous session" are seeded, four of which later commits have made wrong. Each of the 4 tasks is built so that trusting a wrong note gives silently wrong output.

Results:

• Correctness: Mogestrator changed nothing; every run in every cell passed.
• Long sequences: no measurable difference, since the cost ranges overlap.
• Stale notes: they never led the model to wrong code. They made the baseline 59% more expensive, because the agent re-verified every note against the code and git.
• Drift labels: Mogestrator labelled 3 of the 4 wrong memories stale up front. With stale notes that made it 15% cheaper than baseline. With nothing to recall, its session ritual made it 55% more expensive.
• Blind spot: when a file moved, rename tracking re-anchored a memory and labelled it fresh, although its text still named the old path. The current implementation marks moved memories stale for review; the benchmark above predates that fix.

Details: v2 write-up and the v1 pilot. The pilot used in-session subagents with n=2 and measured +29% tokens.

Codex follow-up and long-sequence comparison — 2026-10-06

The new Codex experiment targeted 20 minutes total and completed in 25 min 33 s: one run per arm, the same ten substantive prompts, three sessions, and two teammate commits. Both arms passed every applicable hidden acceptance check.

Four additional gate-failure checks per Codex arm also passed, covering the failure paths skipped by the legacy grader when the echo adapter scores 100%.

Claude token, time, and cost figures are historical means; Codex used codex-cli 0.160.0, gpt-6.1-sol, and high reasoning effort. Codex + Mog processed +49.2% input tokens and took +17.0% wall time in this single pair. Its 11 recoverable CLI lookup failures are included. Codex's resumed-session token totals were differenced to avoid double counting; cached tokens are a subset of input tokens. No dollar estimate was substituted for unavailable billing data.

These are within-client measurements with different models, sample sizes, and memory behavior. They do not establish a client ranking or a significant Codex effect. The seeded stale-notes experiment above remains Claude-only. See the Codex write-up and per-prompt metrics and checks.

Validation and remaining work

CI tests installed packages on macOS, Linux, and Windows with Python 3.11/3.13. Tests exercise real MCP clients over both transports, watch refresh, persistence, stale sources, ingest restrictions, token budgets, and embedding-cache behavior. The optional local BGE backend also has a manually verified smoke path.

python scripts/evaluate_retrieval.py --repo . --dataset tests/fixtures/retrieval_cases.json --output /tmp/retrieval.json runs authored localization smoke cases. Results are recorded in docs/results. These cases are not the pinned real-refactor corpora or B0/B1 comparisons required by EVALUATION.md. M2 remains experimental until those gates pass. Historical M1 performance figures are in ARCHITECTURE.md; they do not describe the latency or index size of this new retrieval implementation.

ROADMAP.md tracks the remaining work: evaluation gates, scalable vectors, complete working-set management, and the policy gateway. M1 indexing, import/co-change links, rename continuity, and the revised size target are complete; see the pinned benchmark. See PLAN.md, SPEC-context-graph.md, SPEC-config.md, and DISTRIBUTION.md.

MIT.