Check if this issue is valid — if so, understand the root cause and fix it. At src/hooks/compaction-context-injector/index.test.ts, line 185:

<comment>The OpenCode SDK expects the path parameter for `session.promptAsync` to be `sessionID`, not `id`. Passing `{ id }` breaks URL path substitution. Update both the test expectation and the underlying implementation.</comment>

<file context>
@@ -104,13 +125,152 @@ describe("createCompactionContextInjector", () => {
+
+      //#then
+      expect(promptAsyncMock).toHaveBeenCalledWith({
+        path: { id: "ses_checkpoint" },
+        body: {
+          noReply: true,
</file context>

Check if this issue is valid — if so, understand the root cause and fix it. At src/features/background-agent/compaction-aware-message-resolver.ts, line 53:

<comment>The `variant` property in the OpenCode SDK is located at the root of the message object (`info.variant`), not within `model`. Reading `info.model?.variant` will silently fail to recover the agent variant from OpenCode message responses. Update the `SessionMessage` type and this mapping logic to extract `variant` directly from `info`.</comment>

<file context>
@@ -16,42 +31,121 @@ function hasFullAgentAndModel(message: StoredMessage): boolean {
+          model: {
+            providerID,
+            modelID,
+            ...(info.model?.variant ? { variant: info.model.variant } : {}),
+          },
+        }
</file context>

Check if this issue is valid — if so, understand the root cause and fix it. At src/features/background-agent/compaction-aware-message-resolver.ts, line 136:

<comment>Synchronously reading and parsing all message files before merging blocks the event loop and degrades performance for long sessions.</comment>

<file context>
@@ -16,42 +31,121 @@ function hasFullAgentAndModel(message: StoredMessage): boolean {
-        continue
-      }
-    }
+    const messages: Array<StoredMessage | null> = []
 
     for (const file of files) {
</file context>

Check if this issue is valid — if so, understand the root cause and fix it. At src/hooks/compaction-context-injector/index.test.ts, line 150:

<comment>The OpenCode SDK defines the `tools` property on messages as `Record<string, boolean>`. The string value `"allow"` is invalid and should be a boolean (e.g., `true`).</comment>

<file context>
@@ -104,13 +125,152 @@ describe("createCompactionContextInjector", () => {
+                role: "user",
+                agent: "atlas",
+                model: { providerID: "openai", modelID: "gpt-5" },
+                tools: { bash: "allow" },
+              },
+            },
</file context>

Check if this issue is valid — if so, understand the root cause and fix it. At src/hooks/compaction-context-injector/tail-monitor.ts, line 1:

<comment>The `MEANINGFUL_ASSISTANT_PART_TYPES` set is missing Opencode SDK's `"thinking"` and `"redacted_thinking"` part types. This will cause extended reasoning messages to be incorrectly treated as empty/no-text tails.</comment>

<file context>
@@ -0,0 +1,52 @@
+const MEANINGFUL_ASSISTANT_PART_TYPES = new Set([
+  "reasoning",
+  "tool",
</file context>

Check if this issue is valid — if so, understand the root cause and fix it. At src/hooks/compaction-context-injector/session-id.ts, line 6:

<comment>Check for `info.sessionID` before falling back to `info.id` to prevent incorrectly returning a message ID when processing message events.</comment>

<file context>
@@ -0,0 +1,8 @@
+}
+
+export function resolveSessionID(props?: Record<string, unknown>): string | undefined {
+  return (props?.sessionID ??
+    (props?.info as { id?: string } | undefined)?.id) as string | undefined
+}
</file context>

Check if this issue is valid — if so, understand the root cause and fix it. At src/hooks/compaction-context-injector/recovery.ts, line 63:

<comment>Failed recovery attempts do not update the cooldown timestamp, causing an infinite loop of prompt injections.</comment>

<file context>
@@ -0,0 +1,143 @@
+      }
+    }
+
+    try {
+      await ctx.client.session.promptAsync({
+        path: { id: sessionID },
</file context>