LemonCrow Runtime

Keep your coding agent sharp on real codebases

Context engineering, done right.

LemonCrow runs underneath Claude Code, Codex, and other supported hosts with a local code graph, exact-range reads, bounded output, durable memory, and verified runtime controls — fully local, no account required.

State-of-the-art context engineering. LemonCrow is tuned end to end across input context and output — ranked retrieval, exact-range reads, and bounded, compacted output — and out-measures grep-class code-index and output-compression tooling on the numbers below (~1.9x retrieval MRR vs ripgrep, 27.9% fewer output tokens on SWE-bench Verified).

License Latest release Stars

Claude Code Codex opencode Copilot Copilot CLI

Quick start · What it does · Limitations · Privacy · Results · Removal

Why I built this

I kept burning my weekly credits before the week was out. Every "token-saving" tool I tried claimed wins but none measured what I actually paid — real dollars, end to end, on real tasks. Token counts aren't a bill.

So I built LemonCrow: a runtime that lives inside your existing agent host, changes nothing about your workflow, and squeezes out the maximum saving it can. Every number below is an absolute-dollar measurement (BENCHMARKS.md) — not a token-count hand-wave.

Quick start

Install from a checksummed GitHub release:

curl -fsSL https://github.com/lemoncrow-lab/lemoncrow/releases/latest/download/install.sh | bash

… or build from source (see Installation):

git clone https://github.com/lemoncrow-lab/lemoncrow
cd lemoncrow
bash scripts/local.sh

Then initialize it inside the project where you use your coding agent — no login, no network:

cd your-project
lc init
lc status

lc init wires better tools into your agent host and registers the repository locally. lc status reports local runtime health. That's it — you're running.

What LemonCrow does

LemonCrow keeps your existing coding agent and changes the working set around it:

Stage Runtime behavior
Find Rank symbols, definitions, callers, callees, usages, and exact source ranges before broad file exploration.
Read Return an outline or only the requested lines; cap noisy command and web output with recoverable spill files.
Carry Preserve useful task state through memory, deduplication, compaction manifests, and handover packets.
Verify Notice code changes without tests or checks, then nudge the agent before it declares completion.

What actually gets replaced

On Claude Code, lc init gives the agent five grounded tools and hides the equivalent built-ins — one way to do each job, not two. Other hosts use the strongest equivalent controls they expose.

LemonCrow tool Replaces (hidden from the model) Why
code_search Grep, Glob One call returns the symbol, its callers/callees, and ranked source — no grep-loop-then-read-whole-file. Ranked by call-graph centrality over a tree-sitter symbol table
read Read Returns an outline or the exact :L10-L40 range, budgeted, instead of the full file
edit Edit, Write Verified, cross-file edits in one call instead of per-file patch-or-create guessing
bash Bash Output is capped and structured so a noisy build log can't blow the context window
web_fetch WebFetch Strips a page to clean Markdown instead of a raw HTML dump

What's unchanged: the host, the model, your workflow. Full internals: Architecture.

Agents

Packaged in integrations/agents/ — each a distinct capability grant (subagent name lemoncrow:<mode>):

Agent Writes? Use
code Yes default interactive — edits, refactors, features
auto Yes fully autonomous — CI/headless runs
solve Yes end-to-end solving of a well-defined task
execute Yes one verified pass of an accepted plan
general Yes catch-all for mixed work
bare Yes minimal toolset, same discipline
explore No read-only exploration — locate and cite
plan No read-only planning, stops for human checkpoint
review No adversarial read-only review
research No external web research — cited memo

Skills

Optional Packaged in integrations/skills/: /lemoncrow, /benchmark, /orchestrate, /swarm, /perf-review, /ux-review, /recall.

Inspect your own sessions

lc session stats     # read-only report of wasted tool calls and round-trips
lc session replay    # replay a recorded session through the real LemonCrow tools

Both are local and read-only — no model re-run, nothing transmitted.

What LemonCrow does not do

  • It is not a hosted service. There is no cloud backend, dashboard account, or team collaboration server.
  • It does not run your model for you — you bring and configure your own provider/API key (Anthropic, OpenAI, Ollama, …).
  • It does not guarantee the benchmark deltas below on your repository; results vary by task, codebase, and model.
  • Some integrations are early or in progress; behavior varies by host (e.g. session-close verification is enforced on Claude Code, advisory elsewhere).

Privacy and network behavior

  • Runs locally. After install, all core functionality works offline and contacts no LemonCrow-controlled server.
  • Telemetry is OFF by default and strictly opt-in. A global DO_NOT_TRACK=1 / LEMONCROW_TELEMETRY=off environment kill switch is honored.
  • No identifier, repository path, source code, or symbol name leaves your machine. There is no crash reporting.
  • The only network calls the runtime makes are ones you initiate (lc update, which checks GitHub Releases).
  • Full detail: docs/privacy.md.

Supported environments

  • Operating systems: Linux and macOS (primary); Windows is partially, never tested.
  • Runtime: Python 3.12–3.13, managed with uv.
  • Agent hosts: Claude Code, Codex and opencode today; Copilot, Cursor, Hermes, and Antigravity are in progress. Any MCP-compatible agent can connect to the same tools.
  • Build requirements: uv, a C toolchain (only if you opt into the mypyc performance build; a pure-Python build works without it), and git.
  • Known limitations: see What LemonCrow does not do and Troubleshooting.

Results

These are fixed results from pinned benchmark runs — not a live counter. Every headline number links back to committed raw runs and methodology in BENCHMARKS.md. The model, tasks, containers, turn limits, and verification harness were held constant. Results are mixed by design and include a regression (SWE-bench Lite below).

Benchmark Baseline correct LemonCrow correct Correct delta Baseline cost LemonCrow cost Cost delta
SWE-bench Verified, 50 tasks x 5 reps 80.8% 92.8% +12.0 pp $234.84 $165.45 29.5% cheaper
SWE-bench Lite, 10 tasks x 5 reps 98.0% 96.0% -2.0 pp $19.83 $17.51 11.7% cheaper
SWE-bench Pro, 10 tasks x 5 reps 88.0% 90.0% +2.0 pp $39.01 $30.61 21.5% cheaper
Exploration tasks across 7 large repos x 5 reps - - - $19.11 $6.29 67% cheaper
Telegraphic Q&A, 20 prompts x 5 reps - - - $8.40 $4.48 46.7% cheaper
Terminal-Bench 2.1, 89 tasks x 5 reps (matched)* 78.9% 80.0% +1.1 pp — — —

* Both arms 89 tasks x 5 reps = 445 trials on the same dataset (LemonCrow's Harbor run vs the Claude Code 2.1.205 leaderboard run), so correctness is directly comparable. LemonCrow also sends 91.8% fewer fresh input tokens (1.05M vs 12.87M); cost is not a matched comparison here — see BENCHMARKS.md.

SWE-bench Verified detail (250 runs a side) — one-shot search collapses the grep-and-read loop, so turns, wall-clock, and tool calls drop together:

Metric Baseline LemonCrow Delta
Turns 6,962 4,336 37.7% fewer
Wall-clock 14.3h 10.9h 23.7% faster
Total tool calls 6,700 4,167 -37.8%
Output tokens 3.04M 2.19M 27.9% fewer

Scale

Indexing throughput and search quality hold up at repository sizes agents actually hit. A cold full rebuild of the Linux kernel core (1.24M symbols, 4.5M lines) and retrieval quality vs grep-class tools on ~7,200 query/answer pairs across 14 repos:

Metric LemonCrow Grep-class baseline
Linux cold index, lexical (1.24M symbols) 179s (~3 min) —
Linux cold index, zoekt trigram 13.7s —
Retrieval MRR (higher = better) 0.727 semantic / 0.676 lexical 0.376 (ripgrep)
Query latency, p95 134ms lexical / 390ms semantic 66ms (ripgrep)

Ranked search is ~1.9x more accurate than ripgrep at a still-interactive p95; ripgrep wins raw latency but not what it finds. Per-repo indexing table and the full 13-tool retrieval comparison: BENCHMARKS.md.

Reproduce any of this from committed raw data: see BENCHMARKS.md and docs/benchmarks/results.md.

Learn more

Removal

Uninstall LemonCrow and its host integrations, preserving your data by default:

bash scripts/uninstall.sh

To also remove all LemonCrow-managed local state (databases, caches, logs, the local installation identifier, and configuration):

bash scripts/uninstall.sh --purge

The uninstaller stops background services, removes user-level systemd/launchd units, removes LemonCrow-owned host-integration entries (without touching unrelated agent-host configuration), reverts LemonCrow's PATH changes, and prints exactly what was removed and preserved. Preview with --dry-run.

License

LemonCrow is free and open-source software under the Apache License, Version 2.0 — in its entirety, including the lemoncrow.pro engine. See LICENSE and NOTICE.