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fix(proxy): stop re-compressing headroom_retrieve output and emitting unredeemable markers#1323

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JerrettDavis merged 7 commits into
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khaosdoctor:fix/ccr-retrieve-recompression
Jun 25, 2026
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fix(proxy): stop re-compressing headroom_retrieve output and emitting unredeemable markers#1323
JerrettDavis merged 7 commits into
headroomlabs-ai:mainfrom
khaosdoctor:fix/ccr-retrieve-recompression

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@khaosdoctor

@khaosdoctor khaosdoctor commented Jun 23, 2026

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Description

Two related CCR problems that both end in unreadable content.

The first one (#1077) is an infinite loop. Any tool output over ~500 bytes gets replaced with a <<ccr:hash>> marker, and you call headroom_retrieve to get the original back. But the proxy then compresses the retrieve response too, so what comes back is a brand new marker. Retrieve that one and you get another marker.

The second one (#1006), the proxy makes two independent decisions per request: SmartCrusher compresses, and the headroom_retrieve tool gets injected. The injection is deferred when there's a frozen message prefix (frozen_message_count > 0), but compression keeps running anyway. So the agent receives [... compressed to N. Retrieve more: hash=...] markers with no headroom_retrieve tool to redeem them.

For #1077, SmartCrusher now skips headroom_retrieve results. Before crushing a tool message (OpenAI role=tool) or tool-result block (Anthropic type=tool_result), it checks whether that tool id maps to the CCR tool, and if so leaves it alone. Retrieved content stays readable.

For #1006, compression and injection are no longer decided in isolation. The injection decision is extracted into should_inject_ccr_tool, which the Anthropic handler calls: when injection was deferred because of a frozen prefix but compression just emitted new markers, it injects the tool anyway, so a marker is never handed to an agent that can't act on it. The existing session-sticky dedup means sessions that already have the tool don't get it re-injected and don't lose their cache.

Closes #1077
Closes #1006

Type of Change

  • Bug fix (non-breaking change that fixes an issue)
  • New feature (non-breaking change that adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation update
  • Performance improvement
  • Code refactoring (no functional changes)

Changes Made

  • headroom/transforms/smart_crusher.py: exempt headroom_retrieve results from compression on both the OpenAI role=tool and Anthropic type=tool_result paths.
  • headroom/proxy/helpers.py: add should_inject_ccr_tool, the deferral-plus-override decision the handler used to inline, so the [BUG] Proxy compresses content and emits retrieval markers when headroom_retrieve tool injection is deferred, causing irrecoverable data loss #1006 behaviour is testable at the decision point.
  • headroom/proxy/handlers/anthropic.py: call should_inject_ccr_tool to couple injection with compression; rename the misleading frozen_prefix= log key to frozen_message_count=.
  • tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py and tests/test_proxy/test_ccr_frozen_prefix_coupling.py: new tests; the frozen-prefix test now drives should_inject_ccr_tool so it would fail if the override were removed.

Testing

  • Unit tests pass (pytest)
  • Linting passes (ruff check)
  • Type checking passes (mypy headroom)
  • New tests added for new functionality
  • Manual testing performed

Test Output

$ uv run --extra dev python -m pytest tests/test_proxy/test_ccr_frozen_prefix_coupling.py tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py -q
5 passed, 1 skipped
ruff: All checks passed!
mypy: Success: no issues found

The SmartCrusher test skips locally because the Rust extension .so is built for a different OS, the same skip the existing SmartCrusher tests take locally. It runs in CI where the extension is built.

Real Behavior Proof

  • Environment: macOS, Python 3.13, this branch.
  • Exact command / steps: uv run --extra dev python -m pytest tests/test_proxy/test_ccr_frozen_prefix_coupling.py tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py -q. The frozen-prefix test calls should_inject_ccr_tool (the function the Anthropic handler now uses) with a frozen prefix and freshly emitted markers, then drives apply_session_sticky_ccr_tool end to end and asserts headroom_retrieve lands in the outbound tools. The exemption test runs a headroom_retrieve tool result through SmartCrusher on both the OpenAI and Anthropic shapes.
  • Observed result: 5 passed, 1 skipped. The retrieve tool is injected even under a frozen prefix once markers exist, and is not injected when no markers were emitted. Removing the handler override flips should_inject_ccr_tool and fails the test.
  • Not tested: a full live proxy session. The behaviours are covered at the decision, transform, and handler-call level by the new tests.

Review Readiness

  • I have performed a self-review
  • This PR is ready for human review

Checklist

  • My code follows the project's style guidelines
  • I have performed a self-review of my code
  • I have commented my code, particularly in hard-to-understand areas
  • I have made corresponding changes to the documentation
  • My changes generate no new warnings
  • I have added tests that prove my fix is effective or that my feature works
  • New and existing unit tests pass locally with my changes
  • I have updated the CHANGELOG.md if applicable

Additional Notes

This one touches compression gating, so it's worth a careful read on the injection coupling, that's the part where a wrong call would re-introduce data loss.

  1. Tool results with no id mapping still compress, marked with # ponytail: comments. Only ids we can positively identify as the CCR tool are exempted.
  2. The injection coupling keys off injector.has_compressed_content, so the tool only shows up when there's actually something to retrieve.

… unredeemable markers

headroomlabs-ai#1077: SmartCrusher.apply() now skips tool_result blocks whose corresponding
tool_use has name == CCR_TOOL_NAME (headroom_retrieve).  Without this guard,
the full retrieved content got compressed into a fresh <<ccr:hash>> marker on
the next turn, creating an infinite retrieval loop.  Guard applies to both
OpenAI-style role=tool messages and Anthropic-style type=tool_result blocks.

headroomlabs-ai#1006: In the Anthropic proxy handler, headroom_retrieve tool injection was
deferred unconditionally when frozen_message_count > 0.  If compression fired
on that same turn and emitted new <<ccr:hash>> markers, the agent had no tool
to redeem them -- silent data loss.  Fix: override the deferral when
injector.has_compressed_content is True (new markers were just produced).
The session-sticky duplicate check in apply_session_sticky_ccr_tool ensures
the tools array is unchanged for sessions that already have the tool, so the
cache miss is limited to the first CCR turn in a frozen-prefix session.
@khaosdoctor khaosdoctor marked this pull request as ready for review June 23, 2026 13:55
Copilot AI review requested due to automatic review settings June 23, 2026 13:55

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Pull request overview

Note

Copilot couldn't run its full agentic review because no GitHub Actions runner was available. Make sure your repository has a runner available to run Copilot's review, or add a copilot-setup-steps.yml file specifying one with the runs-on attribute. See the docs for more details.

Fixes CCR proxy behavior to prevent unreadable content by avoiding re-compression of headroom_retrieve outputs and ensuring retrieval markers are always redeemable.

Changes:

  • Exempt headroom_retrieve tool results from SmartCrusher compression (OpenAI role=tool + Anthropic tool_result).
  • Couple CCR tool injection with marker emission in the Anthropic handler to avoid unredeemable markers under frozen prefixes.
  • Add regression tests for both scenarios and record the fixes in the changelog.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file
File Description
headroom/transforms/smart_crusher.py Skips SmartCrusher compression for tool results identified as headroom_retrieve to prevent infinite marker loops.
headroom/proxy/handlers/anthropic.py Forces tool injection when new CCR markers are emitted despite frozen-prefix deferral.
tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py Adds regression coverage for SmartCrusher “don’t re-crush retrieve output” behavior.
tests/test_proxy/test_ccr_frozen_prefix_coupling.py Adds a regression test intended to cover “no unredeemable markers” under frozen prefixes.
CHANGELOG.md Documents the two CCR bug fixes.

Comment thread tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py Outdated
Comment thread tests/test_proxy/test_ccr_frozen_prefix_coupling.py Outdated
Comment thread tests/test_proxy/test_ccr_frozen_prefix_coupling.py Outdated
Comment thread tests/test_proxy/test_ccr_frozen_prefix_coupling.py Outdated
Comment thread headroom/proxy/handlers/anthropic.py
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PR governance

This PR follows the template and is marked ready for human review.

@github-actions github-actions Bot added the status: needs author action Pull request body or readiness checklist still needs author updates label Jun 23, 2026

@JerrettDavis JerrettDavis left a comment

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The CCR failure modes are real, but this branch needs a little more work before merge.

First, the new frozen-prefix regression does not actually exercise the handler change in headroom/proxy/handlers/anthropic.py. The test rebuilds _must_inject_for_new_markers locally and then calls apply_session_sticky_ccr_tool() directly; if the handler-side override were removed, this test would still pass. Please add coverage that drives the Anthropic pre-upstream/finalization path, or extract the injection-decision helper and test that helper from the handler call site, so #1006 is pinned where the bug lived.

Second, tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py imports pytest twice. ruff check . will normally flag that as a duplicate/redefinition style issue, and this branch currently has only PR-governance checks rather than the full CI matrix. Please clean that up and make sure the added tests/lint can run cleanly.

- extract should_inject_ccr_tool helper so the headroomlabs-ai#1006 injection decision is
  pinned at the handler call site, not re-derived in the test
- rewrite frozen-prefix test to drive the real decision helper
- remove duplicate pytest import and unused was_injected bindings
- rename misleading frozen_prefix= log key to frozen_message_count=
- resolve CHANGELOG conflict; use chopratejas org links
@khaosdoctor

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Good catch on the test, you're right that it would have passed even with the override removed since it rebuilt the condition locally.

I pulled the injection decision out into should_inject_ccr_tool in helpers.py, the Anthropic handler calls it now, and the frozen-prefix test drives that same function. So if the override goes away the helper returns False and the test fails where the bug actually lived.

Also cleaned up the rest: dropped the duplicate import pytest, removed the unused was_injected bindings, and renamed the misleading frozen_prefix= log key to frozen_message_count= since the value is a count. Merged main too, changelog conflict resolved.

@github-actions github-actions Bot added status: ready for review Pull request body is complete and the author marked it ready for human review and removed status: needs author action Pull request body or readiness checklist still needs author updates labels Jun 24, 2026

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Re-reviewed after the feedback fixes. The CCR injection decision is now factored into should_inject_ccr_tool and covered at the decision point, and the retrieve-result exemption covers both OpenAI and Anthropic shapes. I ran uv run --extra proxy --with pytest --with pytest-asyncio python -m pytest tests/test_proxy/test_ccr_frozen_prefix_coupling.py tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py -q: 10 passed. No remaining blocking issues found.

@JerrettDavis JerrettDavis merged commit 43494ff into headroomlabs-ai:main Jun 25, 2026
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@github-actions github-actions Bot mentioned this pull request Jun 25, 2026
chopratejas pushed a commit that referenced this pull request Jun 29, 2026
🤖 I have created a release *beep* *boop*
---


<details><summary>0.28.0</summary>

##
[0.28.0](v0.27.0...v0.28.0)
(2026-06-29)


### Features

* add --disable-kompress-fallback to restore legacy PASSTHROUGH fallback
([#1185](#1185))
([f309244](f309244))
* add first-class OpenCode support (wrap, learn, mcp install)
([#559](#559))
([91cd210](91cd210))
* add HEADROOM_KEEPALIVE_EXPIRY to keep upstream connections warm
([#1124](#1124))
([85786b3](85786b3))
* **azure-foundry:** derive upstream URL from ANTHROPIC_FOUNDRY_RESOURCE
([#1138](#1138))
([e5031b0](e5031b0))
* **cache:** attribute prompt-cache misses to TTL lapse vs prefix change
([#1313](#1313))
([#1343](#1343))
([4658721](4658721))
* **code:** add Perl support to code-aware compressor
([#1125](#1125))
([f39858c](f39858c))
* headroom wrap opencode / unwrap opencode CLI
([#1105](#1105))
([b4571cc](b4571cc))
* **learn:** weight loops in Headroom Learn + RTK-loop eval
([#1160](#1160))
([14e8dc4](14e8dc4))
* **learn:** write per-project learnings to CLAUDE.local.md by default
([#1115](#1115))
([ced75e4](ced75e4))
* **proxy:** add request timeout config
([#738](#738))
([c0745d4](c0745d4))
* **proxy:** pilot hardening — inbound auth, security headers, audit
log, air-gap switch
([#1537](#1537))
([546ab55](546ab55))
* **proxy:** support glob patterns in exclude_tools
([#870](#870))
([#1259](#1259))
([a2159c0](a2159c0))
* **read-maturation:** activity-based hold-back Read maturation
(Mechanism B)
([#1068](#1068))
([723b80c](723b80c))
* **savings:** durable savings ledger + headroom savings command
([#1127](#1127))
([978ffa0](978ffa0))
* **wrap:** add --1m to preserve the 1M context window on wrap claude
([#1158](#1158))
([#1351](#1351))
([b50d9c1](b50d9c1))
* **wrap:** make tokensave the primary coding-task compressor, Serena
the backup
([#1230](#1230))
([dca9853](dca9853))


### Bug Fixes

* **agent-evals:** Phase 0 — coding-agent accuracy A/B framework
([#1037](#1037))
([84f9871](84f9871))
* **agno:** tolerate streaming tool-call SDK objects in parser
([#1312](#1312))
([#1336](#1336))
([5986c22](5986c22))
* **bedrock:** add boto3 1.41 + CRT for aws login credentials
([#1486](#1486))
([4db3bc9](4db3bc9))
* bump codebase-memory-mcp to v0.8.1
([#1284](#1284))
([530318b](530318b))
* **ccr:** make headroom_retrieve a hash-only full-content lookup
([#1532](#1532))
([c2fc4d3](c2fc4d3))
* **ccr:** propagate --no-ccr-marker flag to all compressors
([#1022](#1022))
([#1197](#1197))
([0c9b42a](0c9b42a))
* **ccr:** skip Anthropic marker emission when tool injection is
deferred
([#1273](#1273))
([2cae13d](2cae13d))
* **ci:** extend gitleaks allowlist to cover test fixtures + verified
examples
([#1539](#1539))
([d2565a6](d2565a6))
* **ci:** guarantee model present in test shards to end cache-miss
flakiness
([#1399](#1399))
([2e29c72](2e29c72))
* **ci:** normalize Windows CRLF line endings in PR governance script
([#1012](#1012))
([5194388](5194388))
* **cli:** add explicit UTF-8 encoding to file I/O in wrap commands
([#1126](#1126))
([#1164](#1164))
([a0cb798](a0cb798))
* **cli:** fall back gracefully when embedding-server sidecar is absent
([#1206](#1206))
([38f1404](38f1404))
* **cli:** harden all CLI surfaces + fix docs accuracy
([#1491](#1491))
([bd76235](bd76235))
* **cli:** wire --http2/--no-http2 (HEADROOM_HTTP2) into proxy command
([#1373](#1373))
([e06b616](e06b616))
* **cli:** wire --rpm/--tpm and HEADROOM_RPM/HEADROOM_TPM to the Click
proxy command
([#1375](#1375))
([8aab8f2](8aab8f2))
* **code:** slice tree-sitter byte offsets as UTF-8
([#1332](#1332))
([8238402](8238402))
* **code:** validate Python compressed syntax
([#1302](#1302))
([cbd361d](cbd361d))
* **code:** verify a real parse in tree-sitter availability check
([#1231](#1231))
([#1299](#1299))
([5e0bb69](5e0bb69))
* **codex:** retag threads on init so Codex Desktop history stays
visible ([#961](#961))
([#1349](#1349))
([e6bbc40](e6bbc40))
* **codex:** stop pinning Codex memory MCP to one project db
([#1269](#1269))
([ad7993b](ad7993b))
* **dashboard:** include RTK stats in the historical tab
([#1324](#1324))
([35939c3](35939c3))
* **deps:** remediate dependency CVEs and publish SBOM
([#1509](#1509))
([5771a80](5771a80))
* **docker:** persist session history across container revisions
([#1118](#1118))
([5912d65](5912d65))
* **gemini:** offload compression to the executor
([#1382](#1382))
([615848e](615848e))
* **gemini:** resolve Google model capabilities through ModelRegistry
([#1276](#1276))
([17ecad9](17ecad9))
* **install:** guard install_agent_ensure against duplicate runtime
spawns
([#1301](#1301))
([8da0b4e](8da0b4e))
* **install:** repair macOS launchd restart/start lifecycle
([#1290](#1290))
([da1a397](da1a397))
* **install:** stop duplicating ENTRYPOINT in persistent-docker runtime
command ([#833](#833))
([#1348](#1348))
([feedead](feedead))
* **io:** use UTF-8 with locale fallback and preserve line endings on
config/text I/O
([#1498](#1498))
([1baa04e](1baa04e))
* **kompress:** hard override keeps must-keep tokens regardless of model
score ([#1400](#1400))
([42612c8](42612c8))
* **langchain:** disable streaming on wrapped model during ainvoke()
([#1287](#1287))
([3590046](3590046))
* **mcp:** register managed installs with a resolvable headroom command
([#1386](#1386))
([22def93](22def93))
* **mcp:** report correct savings_percent in headroom_compress
([#1106](#1106))
([f216e43](f216e43))
* **opencode:** write local MCP config
([#1381](#1381))
([6c83790](6c83790))
* **packaging:** move hnswlib to optional [vector] extra so [all] needs
no C++ toolchain
([#1499](#1499))
([80fa086](80fa086))
* patch rtk hook script to use absolute path after register_claude_hooks
([#571](#571))
([b618d2d](b618d2d))
* **perf:** surface RTK/CLI context-tool savings in perf and the session
card ([#1433](#1433))
([9362747](9362747))
* **proxy:** add --protect-tool-results to prevent lossy compression of
exact-output Bash results
([#1374](#1374))
([51d4bcf](51d4bcf))
* **proxy:** add an Anthropic buffered read-timeout override
([#1331](#1331))
([3be2526](3be2526))
* **proxy:** add versionless Vertex AI routes for Claude Code
compatibility
([#1321](#1321))
([bb3e040](bb3e040))
* **proxy:** bind before eager preload so a hung compressor load can't
block startup
([#1500](#1500))
([d5ac07f](d5ac07f))
* **proxy:** build SSL contexts for custom CA bundles
([#1134](#1134))
([561ba17](561ba17))
* **proxy:** forward request-id headers on the streaming path
([#1100](#1100))
([#1258](#1258))
([3d59df7](3d59df7))
* **proxy:** gate CCR retrieve/compress endpoints to loopback
([#1338](#1338))
([acafb2d](acafb2d))
* **proxy:** honor force_kompress routing profile
([#996](#996))
([b4682d6](b4682d6))
* **proxy:** keep large compression results on the critical path
([#296](#296))
([#1352](#1352))
([90734b6](90734b6))
* **proxy:** offload /v1/compress to the compression executor to stop
blocking the loop
([#1501](#1501))
([27e010e](27e010e))
* **proxy:** preserve Responses memory continuations with store=false
([#1103](#1103))
([cdfeeac](cdfeeac))
* **proxy:** queue mid-turn user messages on non-Bedrock streaming path
([#1377](#1377))
([b09f027](b09f027))
* **proxy:** register interceptor in explicit transforms list when
HEADROOM_INTERCEPT_ENABLED
([#1376](#1376))
([55c700c](55c700c))
* **proxy:** report real input tokens on streaming message_start
([#1132](#1132))
([#1305](#1305))
([70cc96a](70cc96a))
* **proxy:** retry upstream 429 with Retry-After on both forwarders
([#1329](#1329))
([90bee89](90bee89))
* **proxy:** retry upstream 529 overloaded like 429 on both forwarders
([#1495](#1495))
([547b15d](547b15d))
* **proxy:** stop re-compressing headroom_retrieve output and emitting
unredeemable markers
([#1323](#1323))
([43494ff](43494ff))
* **proxy:** strip Codex lite header from OpenAI WebSockets
([#1543](#1543))
([5d3803a](5d3803a))
* **read-lifecycle:** persist STALE Read originals in the CCR store
([#1488](#1488))
([9157173](9157173))
* recover persistent proxy feature checks and reject non-Copilot
exchange URL
([#1465](#1465))
([16c638b](16c638b))
* remove agents.md
([#1540](#1540))
([a7d3360](a7d3360))
* respect COPILOT_PROVIDER_TYPE env var when provider_type is auto
([#549](#549))
([24cf256](24cf256))
* restore token-mode compression on frozen prefixes
([#1489](#1489))
([8e0dadf](8e0dadf))
* **router:** degrade to pure-Python detection on native panic
([#1123](#1123))
([#1260](#1260))
([a00fb67](a00fb67))
* **rtk:** stop hook registration timing out on a forked daemon
([#1314](#1314))
([9758817](9758817))
* **smart-crusher:** honor enable_ccr_marker on the opaque-blob path
([#1130](#1130))
([27d6f8e](27d6f8e))
* **subscription:** only reset 5h contribution on real rollover, not API
jitter
([#1255](#1255))
([8d6c175](8d6c175))
* **subscription:** run transcript token scan off the event loop
([#1263](#1263))
([f03021f](f03021f))
* surface output reduction without a restart, and explain $0.00 savings
on Python 3.14
([#1296](#1296))
([c30ec4c](c30ec4c))
* **tests:** reset whole headroom logger subtree so caplog stays
deterministic
([#1117](#1117))
([fda4670](fda4670))
* **tls:** add HEADROOM_TLS_STRICT=0 toggle for corporate SSL inspection
([#1308](#1308))
([#1341](#1341))
([52068dd](52068dd))
* **tokenizers:** price CJK/Kana/Hangul at ~1 token per char in
EstimatingTokenCounter
([#1093](#1093))
([a35fe86](a35fe86))
* **transforms:** gate tool string output from lossy compression
([#1307](#1307))
([#1387](#1387))
([c6c921a](c6c921a))
* **websocket:** harden responses websocket origin handling
([#1481](#1481))
([c632023](c632023))
* **windows:** pin UTF-8 encoding on text-mode subprocess calls
([#1311](#1311))
([d633e81](d633e81))
* **wrap:** add Copilot unwrap command
([#1251](#1251))
([b4fde0c](b4fde0c))
* **wrap:** isolate proxy stdio from proxy.log on Windows
([#1191](#1191))
([959ab0d](959ab0d))
* **wrap:** keep agent savings opt-in
([#1294](#1294))
([b829ceb](b829ceb))
* **wrap:** show the dashboard URL when the proxy is already running
([#1313](#1313))
([b0146c4](b0146c4))


### Performance Improvements

* **compression:** take large cold-start contexts off the synchronous
kompress path
([#1171](#1171))
([#1298](#1298))
([6c68ff4](6c68ff4))
</details>

---
This PR was generated with [Release
Please](https://github.com/googleapis/release-please). See
[documentation](https://github.com/googleapis/release-please#release-please).

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
@khaosdoctor khaosdoctor deleted the fix/ccr-retrieve-recompression branch July 9, 2026 11:51
JerrettDavis added a commit to peterlodri-sec/headroom that referenced this pull request Jul 14, 2026
… unredeemable markers (headroomlabs-ai#1323)

## Description

Two related CCR problems that both end in unreadable content.

The first one (headroomlabs-ai#1077) is an infinite loop. Any tool output over ~500
bytes gets replaced with a `<<ccr:hash>>` marker, and you call
`headroom_retrieve` to get the original back. But the proxy then
compresses the *retrieve response too*, so what comes back is a brand
new marker. Retrieve that one and you get another marker.

The second one (headroomlabs-ai#1006), the proxy makes two independent decisions per
request: SmartCrusher compresses, and the `headroom_retrieve` tool gets
injected. The injection is deferred when there's a frozen message prefix
(`frozen_message_count > 0`), but compression keeps running anyway. So
the agent receives `[... compressed to N. Retrieve more: hash=...]`
markers with no `headroom_retrieve` tool to redeem them.

For headroomlabs-ai#1077, SmartCrusher now skips `headroom_retrieve` results. Before
crushing a tool message (OpenAI `role=tool`) or tool-result block
(Anthropic `type=tool_result`), it checks whether that tool id maps to
the CCR tool, and if so leaves it alone. Retrieved content stays
readable.

For headroomlabs-ai#1006, compression and injection are no longer decided in isolation.
The injection decision is extracted into `should_inject_ccr_tool`, which
the Anthropic handler calls: when injection was deferred because of a
frozen prefix but compression just emitted new markers, it injects the
tool anyway, so a marker is never handed to an agent that can't act on
it. The existing session-sticky dedup means sessions that already have
the tool don't get it re-injected and don't lose their cache.

Closes headroomlabs-ai#1077
Closes headroomlabs-ai#1006

## Type of Change

- [x] Bug fix (non-breaking change that fixes an issue)
- [ ] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring (no functional changes)

## Changes Made

- `headroom/transforms/smart_crusher.py`: exempt `headroom_retrieve`
results from compression on both the OpenAI `role=tool` and Anthropic
`type=tool_result` paths.
- `headroom/proxy/helpers.py`: add `should_inject_ccr_tool`, the
deferral-plus-override decision the handler used to inline, so the headroomlabs-ai#1006
behaviour is testable at the decision point.
- `headroom/proxy/handlers/anthropic.py`: call `should_inject_ccr_tool`
to couple injection with compression; rename the misleading
`frozen_prefix=` log key to `frozen_message_count=`.
- `tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py`
and `tests/test_proxy/test_ccr_frozen_prefix_coupling.py`: new tests;
the frozen-prefix test now drives `should_inject_ccr_tool` so it would
fail if the override were removed.

## Testing

- [x] Unit tests pass (`pytest`)
- [x] Linting passes (`ruff check`)
- [x] Type checking passes (`mypy headroom`)
- [x] New tests added for new functionality
- [ ] Manual testing performed

### Test Output

```text
$ uv run --extra dev python -m pytest tests/test_proxy/test_ccr_frozen_prefix_coupling.py tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py -q
5 passed, 1 skipped
ruff: All checks passed!
mypy: Success: no issues found
```

The SmartCrusher test skips locally because the Rust extension `.so` is
built for a different OS, the same skip the existing SmartCrusher tests
take locally. It runs in CI where the extension is built.

## Real Behavior Proof

- Environment: macOS, Python 3.13, this branch.
- Exact command / steps: `uv run --extra dev python -m pytest
tests/test_proxy/test_ccr_frozen_prefix_coupling.py
tests/test_transforms/test_smart_crusher_ccr_retrieve_exemption.py -q`.
The frozen-prefix test calls `should_inject_ccr_tool` (the function the
Anthropic handler now uses) with a frozen prefix and freshly emitted
markers, then drives `apply_session_sticky_ccr_tool` end to end and
asserts `headroom_retrieve` lands in the outbound tools. The exemption
test runs a `headroom_retrieve` tool result through SmartCrusher on both
the OpenAI and Anthropic shapes.
- Observed result: 5 passed, 1 skipped. The retrieve tool is injected
even under a frozen prefix once markers exist, and is not injected when
no markers were emitted. Removing the handler override flips
`should_inject_ccr_tool` and fails the test.
- Not tested: a full live proxy session. The behaviours are covered at
the decision, transform, and handler-call level by the new tests.

## Review Readiness

- [x] I have performed a self-review
- [x] This PR is ready for human review

## Checklist

- [x] My code follows the project's style guidelines
- [x] I have performed a self-review of my code
- [x] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] I have updated the CHANGELOG.md if applicable

## Additional Notes

This one touches compression gating, so it's worth a careful read on the
injection coupling, that's the part where a wrong call would
re-introduce data loss.

1. Tool results with no id mapping still compress, marked with `#
ponytail:` comments. Only ids we can positively identify as the CCR tool
are exempted.
2. The injection coupling keys off `injector.has_compressed_content`, so
the tool only shows up when there's actually something to retrieve.

---------

Co-authored-by: JD Davis <mxjerrett@gmail.com>
JerrettDavis pushed a commit to peterlodri-sec/headroom that referenced this pull request Jul 14, 2026
🤖 I have created a release *beep* *boop*
---


<details><summary>0.28.0</summary>

##
[0.28.0](headroomlabs-ai/headroom@v0.27.0...v0.28.0)
(2026-06-29)


### Features

* add --disable-kompress-fallback to restore legacy PASSTHROUGH fallback
([headroomlabs-ai#1185](headroomlabs-ai#1185))
([f309244](headroomlabs-ai@f309244))
* add first-class OpenCode support (wrap, learn, mcp install)
([headroomlabs-ai#559](headroomlabs-ai#559))
([91cd210](headroomlabs-ai@91cd210))
* add HEADROOM_KEEPALIVE_EXPIRY to keep upstream connections warm
([headroomlabs-ai#1124](headroomlabs-ai#1124))
([85786b3](headroomlabs-ai@85786b3))
* **azure-foundry:** derive upstream URL from ANTHROPIC_FOUNDRY_RESOURCE
([headroomlabs-ai#1138](headroomlabs-ai#1138))
([e5031b0](headroomlabs-ai@e5031b0))
* **cache:** attribute prompt-cache misses to TTL lapse vs prefix change
([headroomlabs-ai#1313](headroomlabs-ai#1313))
([headroomlabs-ai#1343](headroomlabs-ai#1343))
([4658721](headroomlabs-ai@4658721))
* **code:** add Perl support to code-aware compressor
([headroomlabs-ai#1125](headroomlabs-ai#1125))
([f39858c](headroomlabs-ai@f39858c))
* headroom wrap opencode / unwrap opencode CLI
([headroomlabs-ai#1105](headroomlabs-ai#1105))
([b4571cc](headroomlabs-ai@b4571cc))
* **learn:** weight loops in Headroom Learn + RTK-loop eval
([headroomlabs-ai#1160](headroomlabs-ai#1160))
([14e8dc4](headroomlabs-ai@14e8dc4))
* **learn:** write per-project learnings to CLAUDE.local.md by default
([headroomlabs-ai#1115](headroomlabs-ai#1115))
([ced75e4](headroomlabs-ai@ced75e4))
* **proxy:** add request timeout config
([headroomlabs-ai#738](headroomlabs-ai#738))
([c0745d4](headroomlabs-ai@c0745d4))
* **proxy:** pilot hardening — inbound auth, security headers, audit
log, air-gap switch
([headroomlabs-ai#1537](headroomlabs-ai#1537))
([546ab55](headroomlabs-ai@546ab55))
* **proxy:** support glob patterns in exclude_tools
([headroomlabs-ai#870](headroomlabs-ai#870))
([headroomlabs-ai#1259](headroomlabs-ai#1259))
([a2159c0](headroomlabs-ai@a2159c0))
* **read-maturation:** activity-based hold-back Read maturation
(Mechanism B)
([headroomlabs-ai#1068](headroomlabs-ai#1068))
([723b80c](headroomlabs-ai@723b80c))
* **savings:** durable savings ledger + headroom savings command
([headroomlabs-ai#1127](headroomlabs-ai#1127))
([978ffa0](headroomlabs-ai@978ffa0))
* **wrap:** add --1m to preserve the 1M context window on wrap claude
([headroomlabs-ai#1158](headroomlabs-ai#1158))
([headroomlabs-ai#1351](headroomlabs-ai#1351))
([b50d9c1](headroomlabs-ai@b50d9c1))
* **wrap:** make tokensave the primary coding-task compressor, Serena
the backup
([headroomlabs-ai#1230](headroomlabs-ai#1230))
([dca9853](headroomlabs-ai@dca9853))


### Bug Fixes

* **agent-evals:** Phase 0 — coding-agent accuracy A/B framework
([headroomlabs-ai#1037](headroomlabs-ai#1037))
([84f9871](headroomlabs-ai@84f9871))
* **agno:** tolerate streaming tool-call SDK objects in parser
([headroomlabs-ai#1312](headroomlabs-ai#1312))
([headroomlabs-ai#1336](headroomlabs-ai#1336))
([5986c22](headroomlabs-ai@5986c22))
* **bedrock:** add boto3 1.41 + CRT for aws login credentials
([headroomlabs-ai#1486](headroomlabs-ai#1486))
([4db3bc9](headroomlabs-ai@4db3bc9))
* bump codebase-memory-mcp to v0.8.1
([headroomlabs-ai#1284](headroomlabs-ai#1284))
([530318b](headroomlabs-ai@530318b))
* **ccr:** make headroom_retrieve a hash-only full-content lookup
([headroomlabs-ai#1532](headroomlabs-ai#1532))
([c2fc4d3](headroomlabs-ai@c2fc4d3))
* **ccr:** propagate --no-ccr-marker flag to all compressors
([headroomlabs-ai#1022](headroomlabs-ai#1022))
([headroomlabs-ai#1197](headroomlabs-ai#1197))
([0c9b42a](headroomlabs-ai@0c9b42a))
* **ccr:** skip Anthropic marker emission when tool injection is
deferred
([headroomlabs-ai#1273](headroomlabs-ai#1273))
([2cae13d](headroomlabs-ai@2cae13d))
* **ci:** extend gitleaks allowlist to cover test fixtures + verified
examples
([headroomlabs-ai#1539](headroomlabs-ai#1539))
([d2565a6](headroomlabs-ai@d2565a6))
* **ci:** guarantee model present in test shards to end cache-miss
flakiness
([headroomlabs-ai#1399](headroomlabs-ai#1399))
([2e29c72](headroomlabs-ai@2e29c72))
* **ci:** normalize Windows CRLF line endings in PR governance script
([headroomlabs-ai#1012](headroomlabs-ai#1012))
([5194388](headroomlabs-ai@5194388))
* **cli:** add explicit UTF-8 encoding to file I/O in wrap commands
([headroomlabs-ai#1126](headroomlabs-ai#1126))
([headroomlabs-ai#1164](headroomlabs-ai#1164))
([a0cb798](headroomlabs-ai@a0cb798))
* **cli:** fall back gracefully when embedding-server sidecar is absent
([headroomlabs-ai#1206](headroomlabs-ai#1206))
([38f1404](headroomlabs-ai@38f1404))
* **cli:** harden all CLI surfaces + fix docs accuracy
([headroomlabs-ai#1491](headroomlabs-ai#1491))
([bd76235](headroomlabs-ai@bd76235))
* **cli:** wire --http2/--no-http2 (HEADROOM_HTTP2) into proxy command
([headroomlabs-ai#1373](headroomlabs-ai#1373))
([e06b616](headroomlabs-ai@e06b616))
* **cli:** wire --rpm/--tpm and HEADROOM_RPM/HEADROOM_TPM to the Click
proxy command
([headroomlabs-ai#1375](headroomlabs-ai#1375))
([8aab8f2](headroomlabs-ai@8aab8f2))
* **code:** slice tree-sitter byte offsets as UTF-8
([headroomlabs-ai#1332](headroomlabs-ai#1332))
([8238402](headroomlabs-ai@8238402))
* **code:** validate Python compressed syntax
([headroomlabs-ai#1302](headroomlabs-ai#1302))
([cbd361d](headroomlabs-ai@cbd361d))
* **code:** verify a real parse in tree-sitter availability check
([headroomlabs-ai#1231](headroomlabs-ai#1231))
([headroomlabs-ai#1299](headroomlabs-ai#1299))
([5e0bb69](headroomlabs-ai@5e0bb69))
* **codex:** retag threads on init so Codex Desktop history stays
visible ([headroomlabs-ai#961](headroomlabs-ai#961))
([headroomlabs-ai#1349](headroomlabs-ai#1349))
([e6bbc40](headroomlabs-ai@e6bbc40))
* **codex:** stop pinning Codex memory MCP to one project db
([headroomlabs-ai#1269](headroomlabs-ai#1269))
([ad7993b](headroomlabs-ai@ad7993b))
* **dashboard:** include RTK stats in the historical tab
([headroomlabs-ai#1324](headroomlabs-ai#1324))
([35939c3](headroomlabs-ai@35939c3))
* **deps:** remediate dependency CVEs and publish SBOM
([headroomlabs-ai#1509](headroomlabs-ai#1509))
([5771a80](headroomlabs-ai@5771a80))
* **docker:** persist session history across container revisions
([headroomlabs-ai#1118](headroomlabs-ai#1118))
([5912d65](headroomlabs-ai@5912d65))
* **gemini:** offload compression to the executor
([headroomlabs-ai#1382](headroomlabs-ai#1382))
([615848e](headroomlabs-ai@615848e))
* **gemini:** resolve Google model capabilities through ModelRegistry
([headroomlabs-ai#1276](headroomlabs-ai#1276))
([17ecad9](headroomlabs-ai@17ecad9))
* **install:** guard install_agent_ensure against duplicate runtime
spawns
([headroomlabs-ai#1301](headroomlabs-ai#1301))
([8da0b4e](headroomlabs-ai@8da0b4e))
* **install:** repair macOS launchd restart/start lifecycle
([headroomlabs-ai#1290](headroomlabs-ai#1290))
([da1a397](headroomlabs-ai@da1a397))
* **install:** stop duplicating ENTRYPOINT in persistent-docker runtime
command ([headroomlabs-ai#833](headroomlabs-ai#833))
([headroomlabs-ai#1348](headroomlabs-ai#1348))
([feedead](headroomlabs-ai@feedead))
* **io:** use UTF-8 with locale fallback and preserve line endings on
config/text I/O
([headroomlabs-ai#1498](headroomlabs-ai#1498))
([1baa04e](headroomlabs-ai@1baa04e))
* **kompress:** hard override keeps must-keep tokens regardless of model
score ([headroomlabs-ai#1400](headroomlabs-ai#1400))
([42612c8](headroomlabs-ai@42612c8))
* **langchain:** disable streaming on wrapped model during ainvoke()
([headroomlabs-ai#1287](headroomlabs-ai#1287))
([3590046](headroomlabs-ai@3590046))
* **mcp:** register managed installs with a resolvable headroom command
([headroomlabs-ai#1386](headroomlabs-ai#1386))
([22def93](headroomlabs-ai@22def93))
* **mcp:** report correct savings_percent in headroom_compress
([headroomlabs-ai#1106](headroomlabs-ai#1106))
([f216e43](headroomlabs-ai@f216e43))
* **opencode:** write local MCP config
([headroomlabs-ai#1381](headroomlabs-ai#1381))
([6c83790](headroomlabs-ai@6c83790))
* **packaging:** move hnswlib to optional [vector] extra so [all] needs
no C++ toolchain
([headroomlabs-ai#1499](headroomlabs-ai#1499))
([80fa086](headroomlabs-ai@80fa086))
* patch rtk hook script to use absolute path after register_claude_hooks
([headroomlabs-ai#571](headroomlabs-ai#571))
([b618d2d](headroomlabs-ai@b618d2d))
* **perf:** surface RTK/CLI context-tool savings in perf and the session
card ([headroomlabs-ai#1433](headroomlabs-ai#1433))
([9362747](headroomlabs-ai@9362747))
* **proxy:** add --protect-tool-results to prevent lossy compression of
exact-output Bash results
([headroomlabs-ai#1374](headroomlabs-ai#1374))
([51d4bcf](headroomlabs-ai@51d4bcf))
* **proxy:** add an Anthropic buffered read-timeout override
([headroomlabs-ai#1331](headroomlabs-ai#1331))
([3be2526](headroomlabs-ai@3be2526))
* **proxy:** add versionless Vertex AI routes for Claude Code
compatibility
([headroomlabs-ai#1321](headroomlabs-ai#1321))
([bb3e040](headroomlabs-ai@bb3e040))
* **proxy:** bind before eager preload so a hung compressor load can't
block startup
([headroomlabs-ai#1500](headroomlabs-ai#1500))
([d5ac07f](headroomlabs-ai@d5ac07f))
* **proxy:** build SSL contexts for custom CA bundles
([headroomlabs-ai#1134](headroomlabs-ai#1134))
([561ba17](headroomlabs-ai@561ba17))
* **proxy:** forward request-id headers on the streaming path
([headroomlabs-ai#1100](headroomlabs-ai#1100))
([headroomlabs-ai#1258](headroomlabs-ai#1258))
([3d59df7](headroomlabs-ai@3d59df7))
* **proxy:** gate CCR retrieve/compress endpoints to loopback
([headroomlabs-ai#1338](headroomlabs-ai#1338))
([acafb2d](headroomlabs-ai@acafb2d))
* **proxy:** honor force_kompress routing profile
([headroomlabs-ai#996](headroomlabs-ai#996))
([b4682d6](headroomlabs-ai@b4682d6))
* **proxy:** keep large compression results on the critical path
([headroomlabs-ai#296](headroomlabs-ai#296))
([headroomlabs-ai#1352](headroomlabs-ai#1352))
([90734b6](headroomlabs-ai@90734b6))
* **proxy:** offload /v1/compress to the compression executor to stop
blocking the loop
([headroomlabs-ai#1501](headroomlabs-ai#1501))
([27e010e](headroomlabs-ai@27e010e))
* **proxy:** preserve Responses memory continuations with store=false
([headroomlabs-ai#1103](headroomlabs-ai#1103))
([cdfeeac](headroomlabs-ai@cdfeeac))
* **proxy:** queue mid-turn user messages on non-Bedrock streaming path
([headroomlabs-ai#1377](headroomlabs-ai#1377))
([b09f027](headroomlabs-ai@b09f027))
* **proxy:** register interceptor in explicit transforms list when
HEADROOM_INTERCEPT_ENABLED
([headroomlabs-ai#1376](headroomlabs-ai#1376))
([55c700c](headroomlabs-ai@55c700c))
* **proxy:** report real input tokens on streaming message_start
([headroomlabs-ai#1132](headroomlabs-ai#1132))
([headroomlabs-ai#1305](headroomlabs-ai#1305))
([70cc96a](headroomlabs-ai@70cc96a))
* **proxy:** retry upstream 429 with Retry-After on both forwarders
([headroomlabs-ai#1329](headroomlabs-ai#1329))
([90bee89](headroomlabs-ai@90bee89))
* **proxy:** retry upstream 529 overloaded like 429 on both forwarders
([headroomlabs-ai#1495](headroomlabs-ai#1495))
([547b15d](headroomlabs-ai@547b15d))
* **proxy:** stop re-compressing headroom_retrieve output and emitting
unredeemable markers
([headroomlabs-ai#1323](headroomlabs-ai#1323))
([43494ff](headroomlabs-ai@43494ff))
* **proxy:** strip Codex lite header from OpenAI WebSockets
([headroomlabs-ai#1543](headroomlabs-ai#1543))
([5d3803a](headroomlabs-ai@5d3803a))
* **read-lifecycle:** persist STALE Read originals in the CCR store
([headroomlabs-ai#1488](headroomlabs-ai#1488))
([9157173](headroomlabs-ai@9157173))
* recover persistent proxy feature checks and reject non-Copilot
exchange URL
([headroomlabs-ai#1465](headroomlabs-ai#1465))
([16c638b](headroomlabs-ai@16c638b))
* remove agents.md
([headroomlabs-ai#1540](headroomlabs-ai#1540))
([a7d3360](headroomlabs-ai@a7d3360))
* respect COPILOT_PROVIDER_TYPE env var when provider_type is auto
([headroomlabs-ai#549](headroomlabs-ai#549))
([24cf256](headroomlabs-ai@24cf256))
* restore token-mode compression on frozen prefixes
([headroomlabs-ai#1489](headroomlabs-ai#1489))
([8e0dadf](headroomlabs-ai@8e0dadf))
* **router:** degrade to pure-Python detection on native panic
([headroomlabs-ai#1123](headroomlabs-ai#1123))
([headroomlabs-ai#1260](headroomlabs-ai#1260))
([a00fb67](headroomlabs-ai@a00fb67))
* **rtk:** stop hook registration timing out on a forked daemon
([headroomlabs-ai#1314](headroomlabs-ai#1314))
([9758817](headroomlabs-ai@9758817))
* **smart-crusher:** honor enable_ccr_marker on the opaque-blob path
([headroomlabs-ai#1130](headroomlabs-ai#1130))
([27d6f8e](headroomlabs-ai@27d6f8e))
* **subscription:** only reset 5h contribution on real rollover, not API
jitter
([headroomlabs-ai#1255](headroomlabs-ai#1255))
([8d6c175](headroomlabs-ai@8d6c175))
* **subscription:** run transcript token scan off the event loop
([headroomlabs-ai#1263](headroomlabs-ai#1263))
([f03021f](headroomlabs-ai@f03021f))
* surface output reduction without a restart, and explain $0.00 savings
on Python 3.14
([headroomlabs-ai#1296](headroomlabs-ai#1296))
([c30ec4c](headroomlabs-ai@c30ec4c))
* **tests:** reset whole headroom logger subtree so caplog stays
deterministic
([headroomlabs-ai#1117](headroomlabs-ai#1117))
([fda4670](headroomlabs-ai@fda4670))
* **tls:** add HEADROOM_TLS_STRICT=0 toggle for corporate SSL inspection
([headroomlabs-ai#1308](headroomlabs-ai#1308))
([headroomlabs-ai#1341](headroomlabs-ai#1341))
([52068dd](headroomlabs-ai@52068dd))
* **tokenizers:** price CJK/Kana/Hangul at ~1 token per char in
EstimatingTokenCounter
([headroomlabs-ai#1093](headroomlabs-ai#1093))
([a35fe86](headroomlabs-ai@a35fe86))
* **transforms:** gate tool string output from lossy compression
([headroomlabs-ai#1307](headroomlabs-ai#1307))
([headroomlabs-ai#1387](headroomlabs-ai#1387))
([c6c921a](headroomlabs-ai@c6c921a))
* **websocket:** harden responses websocket origin handling
([headroomlabs-ai#1481](headroomlabs-ai#1481))
([c632023](headroomlabs-ai@c632023))
* **windows:** pin UTF-8 encoding on text-mode subprocess calls
([headroomlabs-ai#1311](headroomlabs-ai#1311))
([d633e81](headroomlabs-ai@d633e81))
* **wrap:** add Copilot unwrap command
([headroomlabs-ai#1251](headroomlabs-ai#1251))
([b4fde0c](headroomlabs-ai@b4fde0c))
* **wrap:** isolate proxy stdio from proxy.log on Windows
([headroomlabs-ai#1191](headroomlabs-ai#1191))
([959ab0d](headroomlabs-ai@959ab0d))
* **wrap:** keep agent savings opt-in
([headroomlabs-ai#1294](headroomlabs-ai#1294))
([b829ceb](headroomlabs-ai@b829ceb))
* **wrap:** show the dashboard URL when the proxy is already running
([headroomlabs-ai#1313](headroomlabs-ai#1313))
([b0146c4](headroomlabs-ai@b0146c4))


### Performance Improvements

* **compression:** take large cold-start contexts off the synchronous
kompress path
([headroomlabs-ai#1171](headroomlabs-ai#1171))
([headroomlabs-ai#1298](headroomlabs-ai#1298))
([6c68ff4](headroomlabs-ai@6c68ff4))
</details>

---
This PR was generated with [Release
Please](https://github.com/googleapis/release-please). See
[documentation](https://github.com/googleapis/release-please#release-please).

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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