Three logically-related sets of proxy changes ship in this branch:
1. Strands integration on the Bedrock path (HeadroomBundle + 4 OpenAI
handler fixes + LiteLLM cache stats + dep pin)
2. /stats MCP aggregation (cross-process events log → proxy summary)
3. Codex compression-failure fail-closed (WS + HTTP /v1/responses)
== 1. Strands integration on the Bedrock path ==
* HeadroomBundle (headroom/integrations/strands/bundle.py): single-helper
MCP wiring for a Strands Agent — Headroom MCP server (headroom_compress
/ headroom_retrieve / headroom_stats) plus optional Serena MCP and
optional in-process compression hook. Constructor builds unstarted
MCPClient instances per server; Strands' Agent owns the subprocess
lifecycle. Default config: MCP enabled, Serena enabled, hook OFF
(proxy is the single source of truth for compression). User-side
integration is two lines in any Strands app.
* headroom/proxy/handlers/openai.py — backend path now:
- calls PrefixCacheTracker.update_from_response (was direct-OpenAI only)
- intercepts CCR headroom_retrieve tool_calls server-side, mirroring
the Anthropic handler pattern; NO silent fallback, re-raises on
CCR errors (per feedback_no_silent_fallbacks)
- works for both non-streaming and streaming paths
* headroom/proxy/handlers/streaming.py: _stream_openai_via_backend now
accepts prefix_tracker + optimized_messages, parses cache stats from
the SSE final-usage frame (cache_creation_input_tokens added to the
state machine), records CCR retrieve feedback via a new
_record_ccr_feedback_from_openai_sse helper. Streaming CCR intercept
is intentionally out of scope (mirrors Anthropic streaming behaviour).
* headroom/backends/litellm.py: send_openai_message response usage block
now carries cache_read_input_tokens / cache_creation_input_tokens
(Anthropic/Bedrock dialect) and prompt_tokens_details.cached_tokens
(OpenAI dialect). Backwards-compatible — cold-start callers see the
same 3-key shape; cache keys appear only when the underlying provider
returns them. Pinned by test_no_cache_fields_means_no_cache_keys.
* headroom/proxy/auth_mode.py: ("strands-agents/", "strands") added to
CLIENT_UA_MAP. Production callers should also set X-Client: strands
since the default openai-python UA carries no Strands signal.
* pyproject.toml: huggingface-hub>=1.5.0,<2.0 pinned in [ml] so a sibling
install (e.g. strands-agents) can't drag the version below the floor
transformers 5.x requires (otherwise Kompress silently goes
"unavailable").
== 2. /stats MCP aggregation ==
* headroom/proxy/cost.py: _aggregate_mcp_events() reads the cross-process
shared events file the Headroom MCP server already writes to and
surfaces summary.mcp with three new keys:
- compressions (count of headroom_compress invocations)
- tokens_removed (sum of input - output across those)
- retrievals (count of headroom_retrieve — the load-bearing
over-compression alarm; if it grows linearly
with turn count, lossy compressors are
dropping info the model actually needs)
Defensive on every axis — missing MCP SDK, missing file, malformed
events, read errors — never blocks /stats.
* examples/strands_bundle_demo.py: stats panel prints the new fields so
the demo shows the full proxy-HTTP + MCP-tool story in one view.
== 3. Codex compression-failure fail-closed protection ==
Reported by Camille (2026-05-21): Codex threads were locking with
"ran out of room in the model's context window" after Headroom's
compression timed out on an oversized response.create frame and
forwarded the original ~1.7 MB frame to the upstream, which then
rejected it. Codex's auto-compact heuristic gates on the upstream-
reported total_usage_tokens (which Headroom had been shrinking on
earlier turns), so its compaction never fired and the thread locked.
Validated against open Codex issues (CLI + Desktop share codex-rs/core):
* #16068 — confirms compaction gates on total_usage_tokens,
estimated_token_count is computed but only logged
* #19806 — confirms image token estimator unbounded, contributes to
the same ContextManager.get_total_token_usage → auto-compaction chain
* headroom/proxy/helpers.py: decide_compression_failure_action() with a
unit-tested decision matrix:
- asyncio.TimeoutError → refuse, always
- non-timeout failure + frame > 256 KiB (configurable) → refuse
- non-timeout failure + small frame → forward (legacy)
Operator escape hatches:
- HEADROOM_WS_FAIL_OPEN_ON_COMPRESSION_FAILURE=1 restores legacy
- HEADROOM_WS_COMPRESSION_FAIL_THRESHOLD_BYTES tunes the threshold
* headroom/proxy/handlers/openai.py (WS /v1/responses): consults the
helper after compression failure. On refuse: close client websocket
code 1009 with "headroom: compression <reason> — please compact
context and retry" reason; set termination_cause for the outer
lifecycle finally; return.
* headroom/proxy/handlers/openai.py (HTTP /v1/responses): same helper.
On refuse: raise HTTPException(413) with a structured error body so
FastAPI's HTTPException handler emits a clean 413. The existing
`except HTTPException: raise` guard in this handler already ensures
the 413 propagates without being swallowed by the 502 catch-all.
Anthropic /v1/messages NOT changed in this branch: no equivalent bug
report on Anthropic-protocol clients, Claude Code (Anthropic-owned)
handles context overflow via its own cache_control/ephemeral
primitives, and Cursor/Aider don't maintain the local-Y estimate the
Codex bug requires. Deferred until a real report lands; the patch is
a one-liner reusing the same helper.
== Tests + verification ==
* tests/test_backends/test_litellm_cache_stats.py — 3 tests pinning
cache-stat surfacing across Anthropic/OpenAI dialects + backwards-
compat for no-cache responses.
* tests/test_proxy/test_openai_backend_path.py — 5 tests (Bedrock cache
fields, OpenAI fallback shape, CCR intercept with provider="openai",
CCR re-raise on exception, streaming signature contract).
* tests/test_proxy/test_mcp_stats_aggregation.py — 5 tests pinning the
aggregator across compress+retrieve mixes, empty events, unknown event
types, missing token fields, and read failures.
* tests/test_proxy/test_compression_failure_action.py — 12 tests pinning
the fail-closed decision matrix (timeout always refuses, small
transient passes through, oversize refuses, env override variants,
custom threshold, invalid threshold falls back, 0/negative ignored).
* examples/strands_bedrock_demo.py — model_id bumped from deprecated
Claude 3 Haiku to Sonnet 4.5 (the deprecated model now errors on
account access).
* examples/strands_via_proxy_demo.py — proxy + Bedrock cache + streaming
smoke test.
* examples/strands_mcp_dispatch_test.py — pure MCP round-trip probe.
* examples/strands_bundle_demo.py — full Strands + HeadroomBundle E2E
demo (this is the shape a real Strands user copies into their app).
Full pytest: 5327 passed, 178 skipped. The previously-failing
test_core_operations.py::TestAddBatch::test_add_batch_basic passes now
that the huggingface-hub pin in pyproject.toml unblocks transformers
imports.
E2E verified live against AWS Bedrock (Sonnet 4.5):
* cache_write=10,438 on turn A → cache_read=10,438 on turn B
* streaming SSE final usage frame carries cache_read_input_tokens
* 78.7% reduction on a 50 KB JSON tool_result via SmartCrusher (
dispatched per-content-type by ContentRouter)
* Strands Agent + HeadroomBundle: model autonomously called
headroom_compress + headroom_retrieve via MCP; CompressionStore
round-trip succeeded; final answer correct.
|
||
|---|---|---|
| .claude-plugin | ||
| .devcontainer | ||
| .github | ||
| benchmarks | ||
| crates | ||
| docker | ||
| docs | ||
| e2e | ||
| examples | ||
| headroom | ||
| plugins | ||
| REALIGNMENT | ||
| scripts | ||
| sdk/typescript | ||
| sql | ||
| tests | ||
| wiki | ||
| .actrc | ||
| .actrc.local.example | ||
| .changelog.md | ||
| .commitlintrc.json | ||
| .dockerignore | ||
| .env.act.example | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitguardian.yaml | ||
| .gitignore | ||
| .pre-commit-config.yaml | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CHANGELOG.md | ||
| claude_analysis_ttl.py | ||
| CODE_OF_CONDUCT.md | ||
| codecov.yml | ||
| CONTRIBUTING.md | ||
| deny.toml | ||
| docker-bake.hcl | ||
| docker-compose.yml | ||
| Dockerfile | ||
| Headroom-2.gif | ||
| headroom-savings.png | ||
| headroom_learn.gif | ||
| HeadroomDemo-Fast.gif | ||
| LICENSE | ||
| llms.txt | ||
| Makefile | ||
| mkdocs.yml | ||
| NOTICE | ||
| PR.md | ||
| pyproject.toml | ||
| README.md | ||
| rust-toolchain.toml | ||
| RUST_DEV.md | ||
| SECURITY.md | ||
| uv.lock | ||
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The context compression layer for AI agents
60–95% fewer tokens · library · proxy · MCP · 6 algorithms · local-first · reversible
Docs · Install · Proof · Agents · Discord · llms.txt
AI agents / LLMs: read /llms.txt here, or fetch the live index / full docs blob.
Headroom compresses everything your AI agent reads — tool outputs, logs, RAG chunks, files, and conversation history — before it reaches the LLM. Same answers, fraction of the tokens.
Live: 10,144 → 1,260 tokens — same FATAL found.
What it does
- Library —
compress(messages)in Python or TypeScript, inline in any app - Proxy —
headroom proxy --port 8787, zero code changes, any language - Agent wrap —
headroom wrap claude|codex|cursor|aider|copilotin one command - MCP server —
headroom_compress,headroom_retrieve,headroom_statsfor any MCP client - Cross-agent memory — shared store across Claude, Codex, Gemini, auto-dedup
headroom learn— mines failed sessions, writes corrections toCLAUDE.md/AGENTS.md- Reversible (CCR) — originals never deleted; LLM retrieves on demand
How it works (30 seconds)
Your agent / app
(Claude Code, Cursor, Codex, LangChain, Agno, Strands, your own code…)
│ prompts · tool outputs · logs · RAG results · files
▼
┌────────────────────────────────────────────────────┐
│ Headroom (runs locally — your data stays here) │
│ ─────────────────────────────────────────────── │
│ CacheAligner → ContentRouter → CCR │
│ ├─ SmartCrusher (JSON) │
│ ├─ CodeCompressor (AST) │
│ └─ Kompress-base (text, HF) │
│ │
│ Cross-agent memory · headroom learn · MCP │
└────────────────────────────────────────────────────┘
│ compressed prompt + retrieval tool
▼
LLM provider (Anthropic · OpenAI · Bedrock · …)
- ContentRouter — detects content type, selects the right compressor
- SmartCrusher / CodeCompressor / Kompress-base — compress JSON, AST, or prose
- CacheAligner — stabilizes prefixes so provider KV caches actually hit
- CCR — stores originals locally; LLM calls
headroom_retrieveif it needs them
→ Architecture · CCR reversible compression · Kompress-base model card
Get started (60 seconds)
# 1 — Install
pip install "headroom-ai[all]" # Python
npm install headroom-ai # Node / TypeScript
# 2 — Pick your mode
headroom wrap claude # wrap a coding agent
headroom proxy --port 8787 # drop-in proxy, zero code changes
# or: from headroom import compress # inline library
# 3 — See the savings
headroom stats
Granular extras: [proxy], [mcp], [ml], [agno], [langchain], [evals]. Requires Python 3.10+.
Proof
Savings on real agent workloads:
| Workload | Before | After | Savings |
|---|---|---|---|
| Code search (100 results) | 17,765 | 1,408 | 92% |
| SRE incident debugging | 65,694 | 5,118 | 92% |
| GitHub issue triage | 54,174 | 14,761 | 73% |
| Codebase exploration | 78,502 | 41,254 | 47% |
Accuracy preserved on standard benchmarks:
| Benchmark | Category | N | Baseline | Headroom | Delta |
|---|---|---|---|---|---|
| GSM8K | Math | 100 | 0.870 | 0.870 | ±0.000 |
| TruthfulQA | Factual | 100 | 0.530 | 0.560 | +0.030 |
| SQuAD v2 | QA | 100 | — | 97% | 19% compression |
| BFCL | Tools | 100 | — | 97% | 32% compression |
Reproduce: python -m headroom.evals suite --tier 1 · Full benchmarks & methodology
60B+ tokens saved by the community — live leaderboard →
Agent compatibility matrix
| Agent | headroom wrap |
Notes |
|---|---|---|
| Claude Code | ● | --memory · --code-graph |
| Codex | ● | shares memory with Claude |
| Cursor | ● | prints config — paste once |
| Aider | ● | starts proxy + launches |
| Copilot CLI | ● | starts proxy + launches |
| OpenClaw | ● | installs as ContextEngine plugin |
Any OpenAI-compatible client works via headroom proxy. MCP-native: headroom mcp install.
When to use · When to skip
Great fit if you…
- run AI coding agents daily and want savings without changing your code
- work across multiple agents and want shared memory
- need reversible compression — originals always retrievable via CCR
Skip it if you…
- only use a single provider's native compaction and don't need cross-agent memory
- work in a sandboxed environment where local processes can't run
Integrations — drop Headroom into any stack
| Your setup | Hook in with |
|---|---|
| Any Python app | compress(messages, model=…) |
| Any TypeScript app | await compress(messages, { model }) |
| Anthropic / OpenAI SDK | withHeadroom(new Anthropic()) · withHeadroom(new OpenAI()) |
| Vercel AI SDK | wrapLanguageModel({ model, middleware: headroomMiddleware() }) |
| LiteLLM | litellm.callbacks = [HeadroomCallback()] |
| LangChain | HeadroomChatModel(your_llm) |
| Agno | HeadroomAgnoModel(your_model) |
| Strands | Strands guide |
| ASGI apps | app.add_middleware(CompressionMiddleware) |
| Multi-agent | SharedContext().put / .get |
| MCP clients | headroom mcp install |
What's inside
- SmartCrusher — universal JSON: arrays of dicts, nested objects, mixed types.
- CodeCompressor — AST-aware for Python, JS, Go, Rust, Java, C++.
- Kompress-base — our HuggingFace model, trained on agentic traces.
- Image compression — 40–90% reduction via trained ML router.
- CacheAligner — stabilizes prefixes so Anthropic/OpenAI KV caches actually hit.
- IntelligentContext — score-based context fitting with learned importance.
- CCR — reversible compression; LLM retrieves originals on demand.
- Cross-agent memory — shared store, agent provenance, auto-dedup.
- SharedContext — compressed context passing across multi-agent workflows.
headroom learn— plugin-based failure mining for Claude, Codex, Gemini.
Pipeline internals
Headroom exposes one stable request lifecycle across compress(), the SDK, and the proxy:
Setup → Pre-Start → Post-Start → Input Received → Input Cached → Input Routed → Input Compressed → Input Remembered → Pre-Send → Post-Send → Response Received
- Transforms do the work: CacheAligner, ContentRouter, SmartCrusher, CodeCompressor, Kompress-base, IntelligentContext / RollingWindow.
- Pipeline extensions observe or customize lifecycle stages via
on_pipeline_event(...). - Compression hooks sit alongside the canonical lifecycle as an additional extension seam.
- Proxy extensions remain the server/app integration seam for ASGI middleware, routes, and startup policy.
Provider and tool-specific behavior lives under headroom/providers/ so core orchestration stays focused on lifecycle, sequencing, and policy.
- CLI/tool slices:
headroom/providers/claude,copilot,codex,openclaw - Provider runtime slices:
headroom/providers/claude,gemini, plus shared backend/runtime dispatch inheadroom/providers/registry.py - Core files stay orchestration-first:
wrap.py,client.py,cli/proxy.py, andproxy/server.pydelegate provider-specific env shaping, API target normalization, backend selection, and transport dispatch.
Install
pip install "headroom-ai[all]" # Python, everything
npm install headroom-ai # TypeScript / Node
docker pull ghcr.io/chopratejas/headroom:latest
Granular extras: [proxy], [mcp], [ml] (Kompress-base), [agno], [langchain], [evals]. Requires Python 3.10+.
Using pipx? Choose a supported interpreter explicitly:
pipx install --python python3.13 "headroom-ai[all]"
→ Installation guide — Docker tags, persistent service, PowerShell, devcontainers.
headroom learn
headroom learn — mines failed sessions, writes corrections to CLAUDE.md / AGENTS.md / GEMINI.md.
Documentation
| Start here | Go deeper |
|---|---|
| Quickstart | Architecture |
| Proxy | How compression works |
| MCP tools | CCR — reversible compression |
| Memory | Cache optimization |
| Failure learning | Benchmarks |
| Configuration | Limitations |
Compared to
Headroom runs locally, covers every content type, works with every major framework, and is reversible.
| Scope | Deploy | Local | Reversible | |
|---|---|---|---|---|
| Headroom | All context — tools, RAG, logs, files, history | Proxy · library · middleware · MCP | Yes | Yes |
| RTK | CLI command outputs | CLI wrapper | Yes | No |
| lean-ctx | CLI commands, MCP tools, editor rules | CLI wrapper · MCP | Yes | No |
| Compresr, Token Co. | Text sent to their API | Hosted API call | No | No |
| OpenAI Compaction | Conversation history | Provider-native | No | No |
Attribution. Headroom ships with the excellent RTK binary for shell-output rewriting —
git show --short, scopedls, summarized installers. Huge thanks to the RTK team; their tool is a first-class part of our stack, and Headroom compresses everything downstream of it. Headroom can also use lean-ctx as the selected CLI context tool; setHEADROOM_CONTEXT_TOOL=lean-ctxbefore runningheadroom wrap ....
Contributing
git clone https://github.com/chopratejas/headroom.git && cd headroom
pip install -e ".[dev]" && pytest
Devcontainers in .devcontainer/ (default + memory-stack with Qdrant & Neo4j). See CONTRIBUTING.md.
Community
- Live leaderboard — 60B+ tokens saved and counting.
- Discord — questions, feedback, war stories.
- Kompress-base on HuggingFace — the model behind our text compression.
License
Apache 2.0 — see LICENSE.