9f837d298b
Conflicts resolved toward the PM model: main's lazy_deps/update_cmd_deps/npm
stamp machinery stays deleted (PM + scripts/build/node-deps.mjs own it), the
systemd ExecStop stop-mark rides the installation launcher, legacy
linux_only/macos_only/windows_only markers are rewritten to platforms(), and
finalize_update_receipt carries pending manual-serve obligations forward
again (lost when the ContextVar receipt rewrite crossed c0aa3ce354).
Test harness: the real-home I/O guard exempts /proc/<pid>/fd metadata reads
(deleted-WAL holder scans) and run_tests.sh drops ~/.hermes PATH entries so
shutil.which() cannot trip the tripwire.
95 lines
3.9 KiB
Markdown
95 lines
3.9 KiB
Markdown
# Langfuse Observability Plugin
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This plugin ships bundled with Hermes but is **opt-in** — it only loads when
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you explicitly enable it.
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## Enable
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```bash
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# Interactive: credentials + PM preparation of the langfuse extra + enable
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hermes tools # → Langfuse Observability
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```
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Restart Hermes after setup. If dependency preparation fails, retry through
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`hermes tools`; do not inject the SDK into the selected environment with pip.
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For manual source-checkout setup, see the
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[plugin guide](../../../website/docs/user-guide/features/built-in-plugins.md#observabilitylangfuse).
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## Required credentials
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Set these in `~/.hermes/.env` (or via `hermes tools`):
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```bash
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HERMES_LANGFUSE_PUBLIC_KEY=pk-lf-...
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HERMES_LANGFUSE_SECRET_KEY=sk-lf-...
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HERMES_LANGFUSE_BASE_URL=https://cloud.langfuse.com # or your self-hosted URL
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```
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Without the SDK or credentials the hooks no-op silently — the plugin fails
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open.
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## Verify
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```bash
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hermes plugins list # observability/langfuse should show "enabled"
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hermes chat -q "hello" # then check Langfuse for a "Hermes turn" trace
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```
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Generation observations include the Hermes system prompt when the provider
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uses a separate `system` param (Anthropic Messages API). Open an **LLM call**
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child span to inspect `role: system` (truncated via `HERMES_LANGFUSE_MAX_CHARS`).
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## Optional tuning
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```bash
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HERMES_LANGFUSE_ENV=production # environment tag
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HERMES_LANGFUSE_RELEASE=v1.0.0 # release tag
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HERMES_LANGFUSE_SAMPLE_RATE=0.5 # sample 50% of traces
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HERMES_LANGFUSE_MAX_CHARS=12000 # max chars per field (default: 12000)
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HERMES_LANGFUSE_MAX_DEPTH=4 # max payload depth (default: 4)
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HERMES_LANGFUSE_CAPTURE=sanitized # content capture mode (see below)
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HERMES_LANGFUSE_DEBUG=true # verbose plugin logging
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```
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`HERMES_LANGFUSE_MAX_DEPTH` controls nested payload capture in both `sanitized`
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and `full` modes, including tool arguments and JSON tool results. The root is
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depth 0; each dictionary value or array element adds one level. Values beyond
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the limit become `<max-depth>`, including scalars. For deeper MCP responses,
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set it to a higher non-negative integer (for example, `10`) in the Hermes
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process environment. Unset or blank values default to `4`; invalid or negative
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values log a warning and fall back to `4`. `0` keeps only the root level.
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Increasing the depth exports more content and may produce larger traces;
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secret redaction, string-length limits, and the 50-item collection limit remain
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unchanged. `metadata` mode still omits content.
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## Capture modes
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`HERMES_LANGFUSE_CAPTURE` controls how much *content* (prompts, responses,
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tool arguments/results) is exported. Structural metadata — IDs, roles, tool
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names, token usage, cost, timing — is always captured in every mode.
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| mode | behavior |
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|------|----------|
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| `metadata` | No content. Each content field is replaced by a shape/size stub (`{"omitted": true, "type": "text", "chars": N}`). |
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| `sanitized` | **(default)** Content is exported after secret-pattern redaction (API keys, tokens, JWTs, private keys, `password=`-style assignments) and truncation. Redaction runs *before* truncation. |
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| `full` | Raw content, truncated only. Explicit opt-in — traces will contain whatever passed through the conversation, including injected memory and file contents. |
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The active mode is recorded on every trace as `metadata.capture_mode`.
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Note: `sanitized` is pattern-based defense in depth, not a DLP guarantee.
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For personal sessions or shared Langfuse projects, prefer `metadata`.
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## Error + shutdown coverage
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- Failed model requests (`api_request_error` hook) close their generation
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with `level=ERROR`, status code, retry counters, and a capture-mode-scrubbed
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error message. Non-retryable failures also finish the turn trace.
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- Session end/finalize closes any still-open traces for that session and
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flushes queued events, so interrupted or tool-only turns don't dangle.
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## Disable
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```bash
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hermes plugins disable observability/langfuse
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```
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