fix(ralph-loop): detect completion promise from session messages API (#413)

* fix(ralph-loop): detect completion promise from session messages API

The completion promise (e.g., <promise>DONE</promise>) was not being detected
because assistant text messages were never recorded to the transcript file.
Only user messages, tool uses, and tool results were recorded.

This fix adds a new detection method that fetches session messages via the
OpenCode API and checks assistant text messages for the completion promise.
The transcript file check is kept as a fallback.

Fixes #412

* refactor(ralph-loop): address review feedback

- Simplify response parsing to use response.data consistently (greptile)
- Add session ID tracking to messages mock for better test coverage (cubic)
- Add assertion to verify correct session ID is passed to API

---------

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/hooks/ralph-loop/index.ts

@@ -18,6 +18,17 @@ interface SessionState {
   isRecovering?: boolean
 }
 
+interface OpenCodeSessionMessage {
+  info?: {
+    role?: string
+  }
+  parts?: Array<{
+    type: string
+    text?: string
+    [key: string]: unknown
+  }>
+}
+
 const CONTINUATION_PROMPT = `[RALPH LOOP - ITERATION {{ITERATION}}/{{MAX}}]
 
 Your previous attempt did not output the completion promise. Continue working on the task.
@@ -81,6 +92,41 @@ export function createRalphLoopHook(
     return str.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")
   }
 
+  async function detectCompletionInSessionMessages(
+    sessionID: string,
+    promise: string
+  ): Promise<boolean> {
+    try {
+      const response = await ctx.client.session.messages({
+        path: { id: sessionID },
+        query: { directory: ctx.directory },
+      })
+
+      const messages = (response as { data?: unknown[] }).data ?? []
+
+      if (!Array.isArray(messages)) return false
+
+      const pattern = new RegExp(`<promise>\\s*${escapeRegex(promise)}\\s*</promise>`, "is")
+
+      for (const msg of messages as OpenCodeSessionMessage[]) {
+        if (msg.info?.role !== "assistant") continue
+
+        for (const part of msg.parts || []) {
+          if (part.type === "text" && part.text) {
+            if (pattern.test(part.text)) {
+              return true
+            }
+          }
+        }
+      }
+
+      return false
+    } catch (err) {
+      log(`[${HOOK_NAME}] Failed to fetch session messages`, { sessionID, error: String(err) })
+      return false
+    }
+  }
+
   const startLoop = (
     sessionID: string,
     prompt: string,
@@ -151,14 +197,20 @@ export function createRalphLoopHook(
         return
       }
 
-      // Generate transcript path from sessionID - OpenCode doesn't pass it in event properties
-      const transcriptPath = getTranscriptPath(sessionID)
+      const completionDetectedViaApi = await detectCompletionInSessionMessages(
+        sessionID,
+        state.completion_promise
+      )
 
-      if (detectCompletionPromise(transcriptPath, state.completion_promise)) {
+      const transcriptPath = getTranscriptPath(sessionID)
+      const completionDetectedViaTranscript = detectCompletionPromise(transcriptPath, state.completion_promise)
+
+      if (completionDetectedViaApi || completionDetectedViaTranscript) {
         log(`[${HOOK_NAME}] Completion detected!`, {
           sessionID,
           iteration: state.iteration,
           promise: state.completion_promise,
+          detectedVia: completionDetectedViaApi ? "session_messages_api" : "transcript_file",
         })
         clearState(ctx.directory, stateDir)