fix(mcp): attach mcp_tool/error_code to the remote sink's exception capture

[bitfathers94]

fix(mcp): attach mcp_tool/error_code to the remote sink's exception capture

The remote MCP telemetry sink's captureException call named these two
grouping properties in a comment but never actually sent them, so a
PostHog exception breakdown by tool/cause silently dropped the surface
with the most traffic while the stdio and miner sinks kept reporting.
Extend capturePostHogWorkerError with an optional, scrubbed extra
properties argument and pass mcp_tool/error_code through it, matching
the other two sinks property-for-property. The HTTP middleware path
keeps its existing request_path/request_method shape unchanged.

Closes #10037

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✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-31 13:47:35 UTC}

4 files · 1 AI reviewer · no blockers · readiness 95/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
Fixes a real bug: capturePostHogWorkerError previously ignored the mcp_tool/error_code properties the MCP dispatch sink intended to attach, so the remote sink's PostHog exception breakdown couldn't group by tool/cause the way stdio/miner sinks could. The fix adds a properly scrubbed optional extraProperties parameter, merges it after the fixed properties (so mcp_tool/error_code can't clobber environment/request_path/request_method), and leaves the HTTP middleware path untouched by passing no fourth argument. Tests verify the merge, the scrubbing of secret-shaped extra values, and that the HTTP path still excludes mcp_tool — solid, targeted coverage of both new branches.

Nits — 4 non-blocking

• worker-posthog.ts:112-114 spreads scrubbedExtra after the fixed properties, so a caller-supplied extraProperties could in principle override request_path/request_method/environment if key names ever collided — worth a comment noting this is intentional/relied-upon ordering rather than incidental.
• dispatch-telemetry-sink.ts:99-104 still passes redundant `path`/`method` fields (mcp.tool/${tool}, errorCode) into the fixed WorkerErrorRequestContext alongside the new extraProperties, effectively duplicating mcp_tool/error_code information in two different property names (request_path/request_method vs mcp_tool/error_code) — confirm that's the intended dashboard shape rather than leftover duplication from before the fix.
• Consider a short inline comment at the merge site in worker-posthog.ts confirming extraProperties intentionally cannot override the fixed keys, to prevent a future edit from reordering the spread.
• If the request_path/request_method duplication in dispatch-telemetry-sink.ts is intentional (e.g., for backward dashboard compatibility), note that reasoning in the code comment for future readers.

Decision drivers

• ✅ Code review — No blockers (1 reviewer)
• ✅ Gate result — Passing (No configured blocker found.)

Context & advisory signals — never blocks the verdict

Signal	Result	Evidence
Linked issue	✅ Linked	#10037
Related work	✅ No active overlap found	No same-issue or scoped active PR overlap found.
Change scope	✅ 20/20	Low review scope from cached public metadata (1 linked issue).
Validation posture	⚠️ 20/25	Preflight is ready, but the PR body does not name the validation run.
Contributor workload	✅ 10/10	Author activity: 140 registered-repo PR(s), 99 merged, 3 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	bitfathers94; Gittensor profile; 140 PR(s), 3 issue(s).
Improvement	✅ Minor	risk: clean · value: minor · LLM: moderate

Linked issue satisfaction

Addressed
The diff extends capturePostHogWorkerError with a scrubbed optional extraProperties argument, passes {mcp_tool, error_code} from the dispatch sink matching the stdio/miner property names and defaulting to "unknown_error", and adds tests covering the tool/errorCode capture, the default-code arm, and that the HTTP middleware's request_path/request_method output is unaffected and lacks mcp_tool.

Review context

• Author: bitfathers94
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: TypeScript
• Official Gittensor activity: 140 PR(s), 3 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Start here: Add validation command/output.

Signal definitions

• Related work = same linked issue, overlapping active PRs, or title/path similarity.
• Change scope = cached public metadata such as size labels, draft state, and review-burden hints.
• Validation posture = whether the PR provides enough public validation/test evidence for maintainer review.
• Contributor workload = public contributor activity and cleanup pressure, not a repo-wide quality failure.
• Contributor context = public GitHub/Gittensor identity context; non-Gittensor status is not a blocker.

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_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed}

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[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.50%. Comparing base (e055c59) to head (7782add).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10236      +/-   ##
==========================================
+ Coverage   80.47%   80.50%   +0.02%     
==========================================
  Files         282      284       +2     
  Lines       58856    58924      +68     
  Branches     6978     7002      +24     
==========================================
+ Hits        47366    47434      +68     
  Misses      11199    11199              
  Partials      291      291              

Flag	Coverage Δ
backend	100.00% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/api/worker-posthog.ts	100.00% <100.00%> (ø)
src/mcp/dispatch-telemetry-sink.ts	100.00% <100.00%> (ø)

[loopover-orb]

LoopOver approves — the gate is satisfied and CI is green.