OpenCode push turn-diff and Review labels

[chuks-qua]

Parent

#1621

What to build

OpenCode pushes native turn-diff evidence per turn so Review shows a Live view mid-turn that settles into a labelled Last turn. Where native evidence is absent or invalid, the standard fallback chain applies with an honest source label. No provider pull method is added.

Decision Sources

• Serve OpenCode sessions through a pooled serve + SDK provider #1621 (push diff seam) and its working companion .dev/verification/opencode-serve-architecture.html.
• Show and persist provider-native Codex Last turn diffs #1612: push identity by turn, execution, delivery attempt, revision; snapshot, invalidated, and indeterminate-empty states; settled record one-to-one with the assistant message; byte limit documented; never truncate.
• Add Cursor and fallback parity to Last turn Review #1613: source priority and one normalized comparison with no UI provider branches.
• Needs the server-owned diff service from the Show and persist provider-native Codex Last turn diffs #1612 slice before this can land.

Acceptance criteria

• Journey: open Review mid-turn ÔåÆ Live view updates; complete ÔåÆ settles to Last turn; reopen and reconnect read the same settled record.
• Journey: no native evidence ÔåÆ fallback diff carries a source/fidelity label naming the fallback.
• Journey: agent edits a file the user also touched ÔåÆ Last turn shows only the agent patch while disk keeps both.
• Journey: stop mid-turn clears Live and preserves the last settled turn.
• Provider passes the shared diff conformance suite as second adapter.

Blocked by

• Minimal OpenCode turn over pooled serve #1622 (plus the server-owned diff service from the Show and persist provider-native Codex Last turn diffs #1612 slice)

Key references

• Program: Provider-neutral Codex protocol completeness #1610 (provider completeness) — read before starting; its decisions bind this ticket.
• Spec: Serve OpenCode sessions through a pooled serve + SDK provider #1621 — full contracts, diagrams, and sequencing.
• Visual companion: .dev/verification/opencode-serve-architecture.html in the main worktree (topology, turn sequence, state, contract drafts).
• Upstream docs: https://opencode.ai/docs/server/ and https://opencode.ai/docs/sdk/
• Prior art: Synara opencodeRuntime.ts (pooled serve per cwd) and T3 Code Layers/OpenCodeAdapter.ts plus issues #2691, #3601, #3604 (failure modes to avoid).