fix(llm-client): redact upstream body from client-call span

[eugenn]

What

The libsy.client_call span recorded the full Display text of a failed client call. For LlmClientError::UpstreamHttp, that text includes the raw upstream response body, which may quote request content.

This was observed while reviewing #610. The broader cross-sink logging policy is tracked in #615.

How

Only the buffered LibsyError::ClientCall / LlmClientError::UpstreamHttp path is changed. The span retains the target, HTTP status, and existing error.type, but does not record the upstream body. The original typed error is returned unchanged.

All other error telemetry keeps its existing behavior. The existing redaction helpers remain private; this PR adds no public API and does not change libsy.run, libsy.llm_call, Advisor, SSE, server, runner, Relay, or streaming error handling.

Test

upstream_body_is_redacted_from_the_client_call_span drives a failing classifier client with an upstream body containing a content marker, then verifies that the libsy.client_call span preserves HTTP 500 classification without the marker.

Validated locally:

• cargo fmt --all --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test -p switchyard-llm-client

[coderabbitai]

Walkthrough

The change applies redacted error summaries to Libsy and LLM client telemetry. It makes shared sanitization helpers public and adds tests for upstream HTTP errors, stream errors, and failed-run telemetry.

Changes

LLM error observability redaction

Layer / File(s)	Summary
Expose sanitization helpers and use them in Libsy telemetry crates/libsy/src/algorithms/util/robustness.rs, crates/libsy/src/lib.rs, crates/libsy/src/observability.rs	The sanitization helpers are public and re-exported. Run and model-call telemetry now records sanitized error summaries.
Redact client and stream errors crates/libsy-llm-client/src/observability.rs	Client-call and streaming telemetry now records redacted or fixed summaries. Decode and upstream stream errors retain their classifications without exposing message content.
Validate telemetry redaction crates/libsy-llm-client/tests/observability.rs	Tests verify that echoed HTTP error bodies and in-band stream errors do not appear in spans or logs. Failed-run assertions now expect "test failed".

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🔵 Low · up to 305ec

This change redacts error telemetry while preserving failure classifications. The remaining risk is limited to missing documentation for the newly public redaction helpers, which could lead to incorrect future use but does not affect the implemented redaction behavior.

Poem

A rabbit guards each error trail
With gentle paws, it hides the detail
Streams still show their class and state
Safe summaries pass the gate
Clean logs now dance beneath the moon

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 18 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes a central change: upstream response-body redaction in the client-call span. It does not cover all telemetry redaction changes, but the title does not need to describe ev…

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Actionable comments posted: 1

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Inline comments:
In `@crates/libsy/src/algorithms/util/robustness.rs`:
- Line 24: Add Rustdoc comments for both public functions safe_error_summary and
safe_client_error in crates/libsy/src/algorithms/util/robustness.rs at lines
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📥 Commits

Reviewing files that changed from the base of the PR and between 7a72c06 and 305ecaa.

📒 Files selected for processing (5)

• crates/libsy-llm-client/src/observability.rs
• crates/libsy-llm-client/tests/observability.rs
• crates/libsy/src/algorithms/util/robustness.rs
• crates/libsy/src/lib.rs
• crates/libsy/src/observability.rs

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[afourniernv]

Thanks for catching this. I reproduced the leak, but I think this PR is doing too much in some places and not enough in others.

It makes the existing helper public and strips detail from every libsy error, while the server, Advisor, and SSE paths can still log raw messages.

I opened #615 to track the broader logging behavior. Could we keep this PR focused on the original libsy span leak and leave the helpers private?

[eugenn]

Agreed — I narrowed this to the original libsy.client_call span leak.

The updated PR now changes only the buffered UpstreamHttp recording path and one regression test. The existing helpers stay private, and the libsy.run, libsy.llm_call, streaming, server, Advisor, SSE, runner, and Relay behavior is unchanged here. The broader cross-sink policy remains in #615.

Validated with cargo fmt --all --check, workspace clippy with warnings denied, and cargo test -p switchyard-llm-client.

[afourniernv]

Thanks for the contribution and for tightening the scope here!