kvguard
Catch 1-token prompt-cache misses in real time — and heal them before the request leaves your machine.
Prompt caches (Anthropic, OpenAI) and local KV caches (llama.cpp, Ollama, vLLM) only reuse work when a new prompt starts with exactly the same bytes as the last one. One rotating header, one timestamp, one reshuffled MCP tool list — and 30–80K tokens are billed or prefilled again. Nothing errors. You just pay more and wait longer.
kvguard is a local proxy + terminal UI that shows you where the prefix broke, why, and what it cost — and can rewrite requests so it doesn't break again.
Quick start
uvx kvguard -- claude # Claude Code (observe only)
uvx kvguard --target http://127.0.0.1:8080 -- opencode # any agent → llama-server
uvx kvguard attach # live TUI in a second terminal
The first run downloads the native binary for your platform from GitHub Releases and verifies its SHA-256 checksum. No Docker, no database, no account.
What you see
Turn Branch / Slot Model Prefix Health Hit % Root Cause / Action
#04 main [slot 0] claude-sonnet-4-5 [█░░░░░░░░░] 12% ❌ BUST @ tok ~#418 (volatile header/id in system · system[0].text)
#05 main [slot 0] claude-sonnet-4-5 [██████████] 96% ⚡ HEALED (sorted 48 tools + stripped cch= billing header)
#06 sub-1 [slot 1] claude-haiku-4-5 [··········] – ◆ NEW BRANCH
What it catches
| Cause | Typical source | --heal |
|---|---|---|
| tools[] order shuffled | MCP servers starting asynchronously | ✅ sorted by name |
| schema key order changed | non-deterministic JSON serialization | ✅ RFC 8785 key order |
| volatile header in system | Claude Code cch= billing header on non-Anthropic backends |
✅ stripped |
| timestamp in prefix | Current time: … with seconds |
⚙️ opt-in --pin-timestamps |
| chat-template drift | Qwen/DeepSeek dropping <think> from old turns |
✅ --normalize-think-tags |
| history message mutated | compaction, truncated tool output | 🔎 reported with JSON path |
| sub-agent evicting main KV slot | llama-server with parallel slots | ✅ main pinned to id_slot 0 |
Sub-agents and parallel sessions get their own branch, so they are never reported as false busts.
CI gate
uvx kvguard --record trace.jsonl -- my-agent run-scenario
uvx kvguard check trace.jsonl --fail-on-bust --min-hit-rate 0.95
Prints a Markdown report and exits 1 when a request breaks its parent's prefix.
Supported
Anthropic /v1/messages · OpenAI /v1/chat/completions and /v1/responses · llama.cpp llama-server · Ollama · any OpenAI-compatible server. Prebuilt for Linux (x86_64, arm64), macOS (Intel, Apple Silicon) and Windows (x86_64).
Also available as npx kvguard (npm), pipx run kvguard and as a standalone binary.
Full documentation, accuracy notes and design: https://github.com/tranhoangtu-it/kvguard
License
MIT OR Apache-2.0
1 maintainer
Metadata
1 maintainer
Release files for kvguard 0.3.2
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Source distribution (sdist)
| File | Size | Uploaded | Provenance | Actions |
|---|---|---|---|---|
| kvguard-0.3.2.tar.gz | 4.2 kB | With provenance | Details for kvguard-0.3.2.tar.gz |
Built distribution (wheel)
| File | Interpreter | ABI | Platform | Actions Reset |
|---|---|---|---|---|
| kvguard-0.3.2-py3-none-any.whl | Python 3 | none | any | Details for kvguard-0.3.2-py3-none-any.whl |
Total release size: 9.3 kB
Release files / kvguard-0.3.2.tar.gz
| Download URL | kvguard-0.3.2.tar.gz |
|---|---|
| Size | 4.2 kB |
| Tags | Source |
|
SHA-256 checksum How to use checksums |
28845a267a0c0c160aceff8c4bd96895ace4cc99b6c98e87ede050daae28dd3f
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Yes |
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twine/7.0.0 CPython/3.13.16
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Signed by GitHub Actions, verified by PyPI on Nov 5, 2026.
Transparency logRelease files / kvguard-0.3.2-py3-none-any.whl
| Download URL | kvguard-0.3.2-py3-none-any.whl |
|---|---|
| Size | 5.1 kB |
| Tags | Python 3 |
|
SHA-256 checksum How to use checksums |
4b144f1aefb2f88d7a848335e49b503c7ddfbca4607292012d5246649aca27e3
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Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.16
|
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Signed by GitHub Actions, verified by PyPI on Nov 5, 2026.
Transparency logSecurity for kvguard 0.3.2
Provenance
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Attestation for kvguard-0.3.2.tar.gz
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PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Nov 5, 2026.
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