fix(opencode2): map cloned tool parts back to tool-call/tool-result

[qoole]

Problem

On OpenCode 2, once a session grows large enough for Magic Context to drop or edit-mark tool calls, every later turn in that session fails before it reaches the provider. The host logs:

Failed to drain Session  Error: Schema validation failed
    at SessionModelRequest.prepare

The client shows "working" for a few seconds and then nothing. (The schema dump in that log mentions "Compaction requires either encrypted content or a summary", but that's just one member's annotation printed with the whole union. The actual issue is an AnyOf at content[0] with no sub-issues: a part whose type matches nothing.)

Cause

adaptPayload() converts each tool-call/tool-result pair into a native { type: "tool" } part for the TS pipeline. commit() converts them back by looking each part up in bridges, a Map keyed by object identity.

The drop and edit-marker paths (clampCloneInPlace) deliberately rewrite a structuredClone of the part and swap the clone into parts, to keep the host's live objects untouched. So bridges.get(part) misses the clone, and commit() passes the v1-shaped part through unchanged:

{"type":"tool","callID":"call_…","tool":"read","state":{"input":{"dropped":"[dropped §91§]"},"status":"completed","output":"[dropped §91§]"}}

OpenCode 2's request schema rejects that. On the session where I hit this, 823 of these parts were in the request.

Trailing-blank normalization in strip-content.ts has the same weakness at the message level. It replaces a message with a copy ({ ...message, parts: [...] }), so originals.get(message) misses too, and the host message (its id, and where its tool results go) is lost.

Fix

commit() now also looks up:

• a part's bridge by (message id, callID). The copied message shares the original info, so the id survives. The key is per message, because two turns can reuse a callID. The host's id-less tool-result carriers keep an object key.
• a message's host original by message id.

Behaviour is unchanged whenever the identity lookups succeed.

Tests

src/v2/hooks/payload.test.ts (new) runs the real createToolDropTarget().truncate() and .editMarker() on messages produced by adaptPayload, then checks that commit() emits only V2 content types:

• truncate and edit-marker each map back to a tool-call plus a tool-result carrying the sentinel;
• a callID reused by two turns keeps each turn's own call;
• a message replaced by a copy before commit() keeps its id and its tool-result carrier;
• a no-op pass round-trips the host messages exactly.

Each case fails without its part of the fix. I also checked it by mutation: taking out the id fallback for originals, or keying bridges by object only, fails the relevant tests.

• bun test src/v2/: 42 pass.
• Lint and typecheck pass.
• Full bun test --parallel: 4950 pass, 1 fail. The failure is createCtxSearchTools > explains why commit search is unavailable for a non-repository project, which fails the same way on master in my environment.

Verified on a live host

I tested on OpenCode 2.0.7 with a copy of the affected store: a session of about 1.66M tokens with 823 dropped tool parts. Every turn failed with the error above. With this change (plus #477, needed for this store), the same session completes a turn at about 481k input tokens, and a context-hook probe finds no non-V2 parts.

Related: #477 (stores migrated from 1.x are refused as v1) and #475 (migration 85 relabels real OpenCode 2 rows).

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Summary by cubic

Fixes OpenCode 2 sessions failing once Magic Context drops or edit-marks tool calls, so later turns reach the provider instead of dying with schema validation errors. Behavior is unchanged when identity lookups succeed.

• adaptPayload() now maps cloned tool parts back to V2 tool-call/tool-result pairs by message ID and callID.
• Messages replaced with copies keep their original host message and tool-result carrier.
• Reused callIDs across turns stay scoped to their own message.
• Adds regression tests for truncate, edit-marker, copied-message, and reused-callID cases.

^{Written for commit 9b2abc7. Summary will update on new commits.}

Confidence Score: 5/5

The PR appears safe to merge, with the new fallbacks preserving V2 payload shapes across the documented cloning and message-copying paths.

Summary

This PR makes the OpenCode 2 payload adapter preserve host serialization after the transformation pipeline clones tool parts or copies their owning messages.

• Adds message-scoped tool bridge lookup by message ID and call ID.
• Adds host-message recovery by message ID when object identity is lost.
• Retains object-keyed lookup for id-less tool-result carriers.
• Adds regression coverage for truncation, edit markers, reused call IDs, copied messages, and no-op round trips.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    A[V2 tool-call and tool-result] --> B[adaptPayload]
    B --> C[Native pipeline tool part]
    C --> D{Pipeline preserves identity?}
    D -->|Yes| E[Identity bridge lookup]
    D -->|Part or message cloned| F[Message ID and callID lookup]
    E --> G[commit]
    F --> G
    G --> H[V2 tool-call and tool-result]

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