GH-96: fix(linear): SyncAdapter correctness — TransitionState name→id, paginated idem comment scan, on-or-after delta (post-merge review of #94)

[alekspetrov]

Summary

Automated PR created by Pilot for task GH-96.

Closes #96

Changes

GitHub Issue GH-96: fix(linear): SyncAdapter correctness — TransitionState name→id, paginated idem comment scan, on-or-after delta (post-merge review of #94)

Context

PR #94 (Linear SyncCapable, issue #92) merged with three correctness defects found in post-merge review (2026-07-13). Nothing consumes SyncCapable yet (sync engine is a later milestone), so fixes are non-breaking.

Implementation

All in sdk/integrations/linear/sync.go:

1. TransitionState name→id resolution (round-trip broken today): IssueSnapshot.State carries the workflow state NAME, but TransitionState (sync.go:332) passes providerState straight to Client.UpdateIssueState, which sends GraphQL stateId — writing back a read state name fails the mutation. Resolve name→state-UUID via a per-team workflow-state lookup (pattern: resolveTeamID / GetTeamDoneStateID), accept BOTH a state id and a name, and add a test for the name path.
2. AddComment idempotency scan must paginate: SyncIssueComments (sync.go:349-357) fetches only the default comments page (~50); a pilot-op marker beyond it is missed → duplicate repost on retry. Follow the comments connection cursor (or newest-first with explicit cap + doc). Add a multi-page idempotency test.
3. Delta semantics must match the core contract (on-or-after): implementation uses updatedAt: { gt: $since } with RFC3339 second truncation — an issue updated exactly at the whole-second watermark is silently dropped (lost-update class). Switch to gte + time.RFC3339Nano (UTC); callers dedupe by NativeID. Update the method doc comment in lockstep.
4. (From review nits, cheap while in there): UpdateFields must return an error for unrecognized keys / wrongly-typed values instead of silently dropping them and returning a fresh snapshot as if applied.

Acceptance

• TransitionState succeeds with both a state UUID and a state name (mocked resolution test)
• Idempotent AddComment across >1 comments page (mocked multi-page test)
• Delta test: issue with updatedAt exactly == since is returned; doc says on-or-after
• UpdateFields with an unknown key returns an error, applies nothing
• Existing GH-92: feat(linear): implement SyncCapable — cursor-followed delta, taxonomy StateGroup, field writes #94 tests stay green; api.golden untouched

Refs

• Review source: post-merge review of PR GH-92: feat(linear): implement SyncCapable — cursor-followed delta, taxonomy StateGroup, field writes #94 · Contract: sdk/core/sync.go (feat(core): SyncCapable contract — IssueSnapshot/SyncSource/SyncWriter for board sync (types only) #83) · Sibling defects: github fix issue filed alongside

Planned Steps (execute all in sequence)

• Step 1: fix(linear): SyncAdapter correctness — state name→id, paginated idem scan, on-or-after delta, UpdateFields validation — Fix all four post-merge review defects in sdk/integrations/linear/sync.go as one atomic change (single file, tightly coupled tests): (1) TransitionState name→id — accept both state UUID and state name in TransitionState; add a per-team workflow-state lookup (following the resolveTeamID / GetTeamDoneStateID pattern already in the package) to resolve name→UUID before calling Client.UpdateIssueState; keep the UUID path fast by skipping lookup if input already looks like a UUID. (2) Paginated idempotency scan — in SyncIssueComments (sync.go:349-357), follow the comments connection cursor to scan all pages for the pilot-op marker (or newest-first with an explicit documented cap) to prevent duplicate reposts when the marker sits beyond the first page. (3) On-or-after delta — switch the delta query from updatedAt: { gt: $since } to { gte: $since } and format the timestamp as time.RFC3339Nano in UTC; update the ListChangedSince doc comment to state on-or-after semantics and note that callers dedupe by NativeID. (4) UpdateFields validation — return a wrapped error for unrecognized field keys or wrongly-typed values instead of silently ignoring them, with no partial application on error. Add tests in the same package's _test.go: TransitionState succeeds with a state UUID input; TransitionState succeeds with a state name input (mocked workflow-state resolution); AddComment idempotent when the marker is on page 2 (mocked multi-page comments connection); Delta returns an issue whose updatedAt equals since exactly; UpdateFields with unknown key returns an error and mutates nothing; all existing GH-92: feat(linear): implement SyncCapable — cursor-followed delta, taxonomy StateGroup, field writes #94 tests remain green and sdk/core/api.golden stays untouched.