fix(opencode-plugin): correct session.messages response shape and update tests

[apnea]

Summary

Fix the opencode plugin's getSessionMessages function, which had two bugs that prevented auto-retain from functioning since it was introduced in #853.

The bugs

1. Wrong response shape (hooks.ts:131)

The code read msg.role but the opencode SDK returns messages wrapped as { info: { role }, parts }. This caused a runtime TypeError: Cannot read properties of undefined (reading 'role') every time getSessionMessages was called.

2. Mismatched TypeScript type for SDK call (hooks.ts OpencodeClient type)

The production code correctly calls opencodeClient.session.messages({ path: { id: sessionId } }), but the TypeScript type declaration for that function specified { sessionID: string } — a completely different signature. The type definition did not match the actual call. This was a type error that would have been caught at compile time with stricter type checking.

Impact

Auto-retain and pre-compaction retain were non-functional from the point the plugin was introduced. Every call to getSessionMessages threw a TypeError that was silently caught, returning an empty array. The handleSessionIdle and compaction hooks then exited early at the if (!messages.length) return check. The tools (retain/recall/reflect) and system transform hook were unaffected.

The original test mocks used the same incorrect { role } shape, so all tests passed despite the code not matching the real SDK contract.

Changes

• hooks.ts: Fix OpencodeClient type to match the real SDK, read msg.info.role instead of msg.role
• hooks.test.ts: Update all mock message shapes to { info: { role }, parts }

Testing

• 89/89 tests pass in a clean Docker environment (node:20, fresh clone from remote)
• Manually verified auto-retain fires correctly in a live opencode session

[nicoloboschi]

we should support 1.3.x versions still

[apnea]

Hi @nicoloboschi , the plugin is built against @opencode-ai/sdk@1.3.13. I'm not sure what you mean.

[nicoloboschi]

Hi @nicoloboschi , the plugin is built against @opencode-ai/sdk@1.3.13. I'm not sure what you mean.

I thought opencode changed the message format but I was wrong, sorry, merging now