[mobile] Fix data readiness JSON response errors

[Asherlc]

Summary

• Adds mobile tRPC transport diagnostics for empty JSON responses and JSON parser failures.
• Prevents raw Unexpected end of JSON input from surfacing in data readiness errors by including the tRPC path, status, and content type.
• Adds regression coverage for empty sync.dataHealth responses and invalid JSON response bodies.

Validation

• pnpm lint
• pnpm tsc --noEmit
• cd packages/server && pnpm tsc --noEmit
• cd packages/web && pnpm tsc --noEmit
• pnpm vitest run --project mobile packages/mobile/lib/trpc-fetch.test.ts
• pnpm test:mobile
• pnpm vitest run --project integration packages/server/src/routers/router-data.integration.test.ts

Note: full pnpm test reached 705 passing files and then hit the local ClickHouse 3 GiB memory cap in router-data.integration.test.ts; that suite passed when rerun in isolation with .env.local exported.

---

Summary by cubic

Improves mobile tRPC fetch diagnostics by replacing JSON parsing with clearer errors for empty or invalid bodies, including the tRPC path, HTTP status, and content type. Also reports JSON parse failures to telemetry.

• Bug Fixes

  • Wraps response.json() to detect empty bodies (including whitespace-only) and throw an actionable error.
  • Converts JSON parse failures into a diagnostic Error with the original SyntaxError as cause, and reports it via telemetry.
  • Handles 204/205/304 or zero-length bodies consistently; valid JSON responses remain unchanged.

• Tests

  • Adds tests for 204 empty responses, whitespace-only bodies, and invalid JSON (verifies cause and telemetry capture).

^{Written for commit c0df2f0. Summary will update on new commits.}

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of JSON API responses with no body, now returning a clearer error instead of failing unexpectedly.
  • Enhanced error messages for invalid JSON responses so they better identify the affected request and response status.
• Tests
  • Added coverage for empty JSON responses and JSON parsing failures.

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[coderabbitai]

📝 Walkthrough

Walkthrough

createTrpcFetch in trpc-fetch.ts now validates JSON responses for empty bodies and wraps response.json() with parse-error diagnostics that include the tRPC procedure path and HTTP status/content-type. Two corresponding test cases were added.

Changes

trpcFetch JSON diagnostics

Layer / File(s)	Summary
Empty-body detection and JSON parse diagnostics packages/mobile/lib/trpc-fetch.ts	Adds responseHasEmptyBody (checks status 204/205/304 or content-length: "0") and withJsonParseDiagnostics (monkey-patches response.json() to rethrow parse errors with path/status/content-type). createTrpcFetch now throws on empty JSON responses instead of returning the raw response, and wraps non-empty JSON responses with the diagnostics helper.
Empty-body and parse-error tests packages/mobile/lib/trpc-fetch.test.ts	New tests assert rejection with an "empty response" message for a 204 JSON response, and assert JSON parse errors are rewritten to include the tRPC path and status/content-type.

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

Possibly related PRs

• Asherlc/dofek#1252: Both PRs modify createTrpcFetch in the same file to enrich thrown errors with tRPC path/status diagnostics, one for non-JSON responses and this one for empty/malformed JSON bodies.

Suggested labels: area/mobile, type/bug

Suggested reviewers: cubic-dev-ai

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title is imperative, correctly prefixed with [mobile], under 70 characters, and accurately reflects the JSON response error fix.

---

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[github-actions]

Storybook previews for 0334f1db are ready:

• Web Storybook
• Mobile Storybook

This comment updates automatically on each PR push.

[github-actions]

Mobile Preview

Scan to open on device:

Channel	pr-1460
Deep Link	dofek://preview/pr-1460
Commit	0334f1d

To test on device:

1. Build and install the preview client: PREVIEW_CHANNEL=pr-1460 pnpm expo prebuild --clean -p ios
2. Or tap deep link on an existing preview build: dofek://preview/pr-1460

Each PR gets its own channel. Build a preview client with PREVIEW_CHANNEL=pr-{N} to test.

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/mobile/lib/trpc-fetch.ts`:
- Around line 12-15: The empty-body detection in responseHasEmptyBody is too
heuristic and misses responses that are truly empty but lack a 204/205/304
status or content-length header. Update parseJsonBody to read response.text()
once and check for an empty/whitespace-only body before JSON.parse, then use
that same single read path for both the empty and invalid response error cases.
Keep the existing helpers like getTrpcPath, buildStatusLabel, and
buildContentTypeLabel for the error messages, but remove the separate
body-heuristic branch in responseHasEmptyBody.
- Around line 50-65: The catch in withJsonParseDiagnostics currently drops the
original JSON parse error and does not report it to Sentry. Update the json
override in withJsonParseDiagnostics to catch the thrown error, call
captureException from ./telemetry with that original exception, and then rethrow
a new error that preserves the original as the cause if possible. Keep the
existing getTrpcPath, buildStatusLabel, and buildContentTypeLabel context in the
final message.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: a980c333-51e9-4d2f-bd71-9f3ffdafa010

📥 Commits

Reviewing files that changed from the base of the PR and between 34ba9af and 16c5556.

📒 Files selected for processing (2)

• packages/mobile/lib/trpc-fetch.test.ts
• packages/mobile/lib/trpc-fetch.ts

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

<sub>Auto-approved: Adds diagnostic error messages for empty or invalid JSON responses in mobile tRPC fetch, with test coverage.

Re-trigger cubic</sub>

[cubic-dev-ai]

0 issues found across 2 files (changes from recent commits).

<sub>Auto-approved: Improves error handling for empty/invalid JSON responses in mobile tRPC fetch with diagnostics and telemetry.

Re-trigger cubic</sub>

[Asherlc]

Addressed CodeRabbit title warning.

• Updated the PR title to [mobile] Fix data readiness JSON response errors.
• Commit with code review fixes: c0df2f0