feat(api): request and session IDs from the frontend, client error endpoint and axiom frontend dashboard

[jplacht]

What and why

Frontend and backend logs can't be joined today: the frontend sends no IDs, CORS would reject them, and a response that fails the frontend's Zod check is logged by the backend as a clean 200. This lets the frontend send a request ID and session ID on every call (logged as request_id / correlation_id, also on the Celery tasks a call queues) and report errors from the browser to a new endpoint, logged as client_error for Axiom.

Changes

• X-Request-ID / X-Correlation-ID accepted when they are UUIDs (canonicalized to lowercase, anything else dropped) and logged as request_id / correlation_id, also on queued tasks
• CORS allows both headers
• POST /client-errors/: no auth, bounded body (unknown keys rejected), logs client_error, returns 204; throttle scope client_error 30/min
• Tests for the middleware, Celery propagation, CORS preflight and the endpoint (204/400/429)

The matching Axiom dashboard (prunplanner-frontend) lives in the workspace repo's axiom/ builder.

How it was verified

QA PASS (2 rounds: full, then scoped to the UUID canonicalization). uv run ruff check, ruff format --check, ty check and pytest (798 passed) green. e2e stack: preflight, IDs in request_finished and client_error, 204 / 400 / 429, expired token still 204, uppercase IDs logged lowercase, invalid IDs replaced.

Deploy order

Backward compatible (new endpoint, optional headers); deploy before the frontend change (obs-02) that sends them.

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 8 complexity · 0 duplication

Metric	Results
Complexity	8
Duplication	0

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🟢 Coverage 96.49% diff coverage · +0.01% coverage variation

Metric	Results
Coverage variation	✅ +0.01% coverage variation (-1.00%)
Diff coverage	✅ 96.49% diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (22b3f7a)	4735	4525	95.56%
Head commit (2a8eb1e)	4791 (+56)	4579 (+54)	95.58% (+0.01%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#69)	57	55	96.49%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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