fix(opencode): resume the OpenCode session on follow-ups instead of starting an empty one

[vdmkotai]

Fixes #3604.

What

The OpenCode adapter never read or emitted a resume cursor, so the upstream ses_… id lived only in process memory. When that in-memory binding was lost — ProviderSessionReaper stopping an idle session (~30 min), or an app/server restart — the next follow-up in the same visible thread was sent to a brand-new, empty OpenCode session. t3code kept rendering its own projection DB, so the user still saw the full history while the model had no context.

This makes the OpenCode adapter resumable, mirroring the existing Grok/Cursor/Codex pattern, entirely within apps/server/src/provider/Layers/OpenCodeAdapter.ts:

• startSession now emits resumeCursor: { schemaVersion, sessionId } on the returned ProviderSession (and sendTurn echoes it), so ProviderService persists it into provider_session_runtime.resume_cursor_json.
• When a cursor is present, startSession validates the id with session.get and re-adopts that session instead of calling session.create. OpenCode scopes history by session id, so prompting the same id restores the full prior conversation.
• A missing/closed session (or any session.get failure) falls back to a fresh session, so a stale cursor can never wedge the thread.
• The start race-cleanup only aborts the upstream session when we actually created it — never one we merely resumed.

Why

This is the documented root cause in #3604 (with DB-level evidence of two OpenCode sessions per visible thread). The persistence/recovery plumbing is already provider-agnostic: ProviderService.startSession falls back to the stored binding cursor when the reactor passes none, so no changes are needed outside the adapter — it just needed the adapter to start producing and consuming a cursor like every other provider already does.

Scope

Intentionally small and focused — 2 files, no contract / persistence / orchestration changes:

• apps/server/src/provider/Layers/OpenCodeAdapter.ts (+118/-20)
• apps/server/src/provider/Layers/OpenCodeAdapter.test.ts (+147) — regression tests for: fresh-session cursor emission, resume re-adopting the persisted id (no create), follow-up turns targeting the resumed id, stale-cursor fallback to create, and malformed/foreign-cursor rejection.

Validation

• tsgo --noEmit clean; OpenCodeAdapter.test.ts (21 tests) plus the full src/provider + src/orchestration suites (531 tests) pass.
• Ran a desktop build carrying this fix for a full day across many OpenCode sessions, including idle-past-reaper and app-restart between turns — every follow-up retained full context, no regressions observed.

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Note

Medium Risk
Changes session lifecycle and error handling in the provider adapter; misclassified errors could still drop context or wedge threads, but scope is limited to OpenCode and is heavily regression-tested.

Overview
Fixes silent loss of model context (#3604) when an in-memory OpenCode binding was dropped (idle reaper, restart) while the UI still showed full thread history.

OpenCode adapter now emits and consumes a durable resumeCursor (schemaVersion + sessionId) on startSession and echoes it from sendTurn, aligned with other providers. On start, a valid cursor triggers session.get to re-adopt the upstream ses_… id, reapplies permissions with session.update for the current runtimeMode, and only calls session.create when there is no cursor, the session is missing (structured 404 / NotFoundError via isOpenCodeNotFound), or the session’s directory does not match the requested cwd. Transient or auth errors from the probe propagate instead of falling back to a new session. Concurrent startSession race cleanup aborts the remote session only when this call created it, not when it resumed a shared session.

Tests extend the OpenCode runtime mock (session.get / session.update, 404 vs 500) and add coverage for cursor emission, resume, stale/malformed cursors, directory mismatch, and isOpenCodeNotFound classification.

^{Reviewed by Cursor Bugbot for commit ed5fadf. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Resume existing OpenCode sessions on follow-up turns instead of starting new ones

• startSession in OpenCodeAdapter.ts now parses a resume cursor and probes the upstream session via session.get before creating a new one.
• On a successful probe, the session is re-adopted and permissions are re-applied via session.update; on a 404 or directory mismatch, a fresh session is created instead.
• Non-404 probe errors (transport, auth, server) propagate rather than silently falling back to a new session.
• sendTurn now includes the resumeCursor (containing schemaVersion and sessionId) in its result so callers can persist it across turns.
• Race condition handling is updated: a losing startSession only aborts the remote session if it created it, not if it merely resumed one.

^{Macroscope summarized ed5fadf.}

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[macroscopeapp]

Approvability

Verdict: Needs human review

This bug fix introduces significant new session management behavior (resumption logic, error classification, permission re-application) that changes runtime control flow. The author has no prior commits to this repository, and the behavioral scope warrants human verification despite comprehensive test coverage.

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[vdmkotai]

Thanks for the reviews — addressed in 7be6629. Three hardening changes, all kept within the adapter:

1. Permission re-application on resume (Cursor Bugbot): session.create was the only place buildOpenCodePermissionRules(runtimeMode) was applied, so re-adopting a session via session.get left it on its original permissions — and ProviderCommandReactor restarts with the persisted cursor on a runtime-mode change. Resume now calls session.update({ sessionID, permission }), so a runtime-mode change takes effect on the re-adopted session.

2. Confirmed-not-found vs. transient errors (macroscope): the SDK client is created with throwOnError: true, so session.get rejects on any non-2xx. The fallback to a fresh session now fires only on a confirmed 404 / NotFoundError; transport/auth/server errors propagate instead of silently resetting a live thread to an empty session (matching [Bug]: OpenCode provider loses thread context on follow-up — t3code starts a new OpenCode session instead of resuming (no durable session binding) #3604's own "surface an explicit error" suggestion).

3. Directory-aware resume: OpenCode routes a prompt to the session's own stored directory, so resuming a session created under a different cwd would silently run there. Resume now starts a fresh session when the re-adopted session's directory differs from the requested cwd.

Tests updated to model throwOnError: true (get rejects, not a result tuple) and add coverage for permission re-application, the cwd-mismatch fallback, and transient-error propagation. Full server provider + orchestration suite green (534 passing).

[cursor]

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