fix: middleware for multi-tenant

[nikhilsinhaparseable]

• add x-p-tenant header only for multi-tenant deployment
• extract tenant id from x-p-tenant (if api key user sends) or intra-cluster-tenant (prism forwards to queriers)
• tenant id to default for single tenant deployment

Summary by CodeRabbit

• Bug Fixes
  • Improved tenant handling during request authentication so tenant information is derived more reliably from supported headers.
  • Adjusted API-key session handling to restore tenant context only in multi-tenant deployments.
  • Standardized single-tenant API-key lookup to use the default tenant consistently.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: f45bd265-080e-415d-a21c-5f539e1f7857

📥 Commits

Reviewing files that changed from the base of the PR and between d0390ce and c1be1bf.

📒 Files selected for processing (1)

• src/handlers/http/middleware.rs

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Walkthrough

Tenant identification in AuthMiddleware now also falls back to the intra-cluster-tenant header (excluding DEFAULT_TENANT). Reinsertion of the TENANT_ID header after API-key session creation is now conditional on multi-tenant mode. In find_api_key_user, single-tenant lookups always use DEFAULT_TENANT rather than an optional tenant_id hint.

Changes

Tenant Header Resolution

Layer / File(s)	Summary
Tenant id capture and conditional header reinsertion src/handlers/http/middleware.rs	Tenant id derivation falls back to the intra-cluster-tenant header (excluding DEFAULT_TENANT), and the TENANT_ID header is reinserted after API-key session setup only when multi-tenant mode is active.
Single-tenant lookup default src/handlers/http/middleware.rs	find_api_key_user's single-tenant branch now always resolves to DEFAULT_TENANT instead of using a passed-in tenant_id hint when present.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• parseablehq/parseable#1712: Also modifies AuthMiddleware's TENANT_ID header set/derive logic during API-key resolution.

Suggested reviewers: parmesant

Poem

A tenant hopped through headers new,
DEFAULT_TENANT filtered from view,
Multi-tenant mode gets its due,
Single-tenant keeps its lane too,
Hoppy code, reviewed and true! 🐇

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is largely incomplete and misses the required issue reference, Description section, rationale, and checklist items.	Add the Fixes #XXXX line, a Description section with goal/rationale/key changes, and complete the testing/comments/docs checklist.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and related to the multi-tenant middleware auth changes, though it is a bit broad.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

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