ModernResultReader, ModernPayloadStore, and extension-based attachment typing (#391, Tasks 8–10) - #447

Part of #391 (milestone 4.0), phase 2 of the migration plan: the modern backend itself. Follows #441 (client + schema) and #443 (the port). The reader is reachable only through direct construction in tests — backend selection is Task 11, the next PR. Do not expect render changes from this PR; nothing routes through the new code yet.

What's here

• ModernResultReader (Task 8): builds ParsedResult from get test-results. Statuses map into the neutral enum (Expected Failure still flattens to unknown downstream, deliberately); multi-repetition status derives from Repetition children, ignoring the parent Test Case's own result — RetryResults reports Passed there for a Failed-then-Passed test, so taking it would turn mixed tests green. The tree renders flat (no synthesized All tests / *.xctest wrappers). One activities subprocess per exact test-case id; a failed query records the new .missingActivities fault rather than shipping a silently gutted report.
• ModernPayloadStore (Task 9): one export attachments call per bundle + the manifest.json join (activity attachment uuid ↔ basename of exportedFileName). No per-payload subprocess, no lock table — only the one-shot export is guarded. Run logs come from get log --type action, rendered from structured messages (the format has no emittedOutput).
• Attachment typing (Task 10): the failable AttachmentType(filenameExtension:) landed in The port: ParsedResult model, LegacyResultReader, and the renderer migration (#391, Tasks 3–5b) #443; this PR adds the cross-backend agreement test and fixes the carried review note — public.data was missing from the legacy UTI fallback table, degrading extensionless data attachments to .unknown.
• Review notes from XCResultToolClient and new-format schema structs (#391) #441/The port: ParsedResult model, LegacyResultReader, and the renderer migration (#391, Tasks 3–5b) #443: XCResultToolError now conforms to LocalizedError (faults and warnings printed NSError boilerplate before); the client's unconditional --path/--schema-version is verified safe for all three invocation shapes used (get test-results, export attachments, get log) — no client change needed.
• Sample app: a parameterized @Test(arguments: [1, 2, 3]) so Arguments nodes stop being fixture-unexercised (measured: 3 nodes in the regenerated fixture). Its argument sets merge into one rendered row; the TestResults header total moves 17 → 18 in CoreTests.

Plan deviation, coordinator-approved: failure text is a join

Measured on Xcode 26.2 fixtures: the activities document carries every assertion failure as a failure-flagged activity row — positioned, timestamped, nested inside the user's activity when the assertion fired there — with only the file:line prefix missing; the tests document's Failure Message node keeps the prefix but has no timestamp. The plan's anti-double-count guard kept the activity title and dropped the message, losing file:line from every modern failure render — contradicting the spec's failureTitlePrefix allow-list entry and the "failure text sources from Failure Message nodes" rule.

As ruled: each message retitles the first unclaimed failure-flagged activity whose title is an exact suffix of the message (document order, first-unmatched-first, recursive so the nested RetryResults case retitles in place), keeping position, nesting, timestamp, attachments, and children. Unmatched messages (skip reasons, expected-failure notes) append as before. No regex extraction of file/line — the string renders as given. Plan and spec amended in this PR; regression tests pin file:line presence on both the plain and the nested case.

Fault discipline

testModernRenderOfEveryFixtureRecordsNoFaults does a full modern-path render of all three fixtures — reader + store, attachments and logs resolved in linking mode — and asserts zero faults and zero unresolved attachments. Structurally absent fields (display names, activity types, suite durations, finish times) never fault; a failed activities query and a failed export still do.

Verification

• Full suite: 65 tests, 0 failures, 2 pre-existing skips (CoreTests.testRetryFunctionalityJunit expectations drift with Xcode version #378 JUnit drift, baseline capture) — legacy paths (LegacyResultReaderTests, CoreTests, SanityTests, fault tests) and modern paths (ModernResultReaderTests ×11, ModernPayloadStoreTests ×5, AttachmentTypeTests ×3) both green.
• Fixtures regenerated via ./prepareTestResults.sh on Xcode 26.2 (17C52), xcresulttool 24514, schema 0.1.0 — the spec's measurement environment.

Refs #391.

🤖 Generated with Claude Code