fix(observe): auto-create session row + surface session/start HTTP errors (closes #522)

plugin/scripts/session-start.mjs

@@ -41,6 +41,8 @@ async function main() {
 		fetch(url, {
 			...init,
 			signal: AbortSignal.timeout(REGISTER_TIMEOUT_MS)
+		}).then((res) => {
+			if (!res.ok) process.stderr.write(`[agentmemory] session/start returned ${res.status} for ${sessionId}\n`);
 		}).catch(() => {});
 		return;
 	}
@@ -52,7 +54,7 @@ async function main() {
 		if (res.ok) {
 			const result = await res.json();
 			if (result.context) process.stdout.write(result.context);
-		}
+		} else process.stderr.write(`[agentmemory] session/start returned ${res.status} for ${sessionId}\n`);
 	} catch {}
 }
 main();

src/functions/observe.ts

@@ -214,6 +214,28 @@ export function registerObserveFunction(
             }
           }
           await kv.update(KV.sessions, payload.sessionId, updates);
+        } else {
+          // Auto-create the session row when an observation arrives before
+          // (or instead of) a successful session/start call. The hook
+          // scripts call session/start as fire-and-forget; on transient
+          // server unavailability that POST is silently dropped, leaving
+          // observations orphaned from GET /agentmemory/sessions even
+          // though they're present on disk. Re-creating here closes the
+          // data-loss hole permanently; session/start remains the fast
+          // path (it also returns the injected context).
+          const firstPrompt =
+            typeof raw.userPrompt === "string"
+              ? raw.userPrompt.replace(/\s+/g, " ").trim().slice(0, 200)
+              : undefined;
+          await kv.set(KV.sessions, payload.sessionId, {
+            id: payload.sessionId,
+            project: payload.project,
+            cwd: payload.cwd,
+            startedAt: payload.timestamp,
+            status: "active",
+            observationCount: 1,
+            ...(firstPrompt ? { firstPrompt } : {}),
+          });
         }
 
         // Per-observation LLM compression is opt-in as of 0.8.8 (#138).

src/hooks/session-start.ts

@@ -62,11 +62,24 @@ async function main() {
   if (!INJECT_CONTEXT) {
     // Pure telemetry path: caller never reads the response, so don't
     // block on it. AbortSignal.timeout caps the wait the event loop
-    // gives the pending socket before exit.
+    // gives the pending socket before exit. Server-side observe now
+    // auto-creates a session row when one is missing (#522), so a
+    // dropped POST here is a missed context-inject, not data loss.
     fetch(url, {
       ...init,
       signal: AbortSignal.timeout(REGISTER_TIMEOUT_MS),
-    }).catch(() => {});
+    })
+      .then((res) => {
+        // Surface HTTP errors so wiring problems (wrong URL, auth)
+        // don't stay invisible. Network/timeout errors fall through
+        // to .catch() and stay quiet — those are common on cold-start.
+        if (!res.ok) {
+          process.stderr.write(
+            `[agentmemory] session/start returned ${res.status} for ${sessionId}\n`,
+          );
+        }
+      })
+      .catch(() => {});
     return;
   }
 
@@ -80,9 +93,14 @@ async function main() {
       if (result.context) {
         process.stdout.write(result.context);
       }
+    } else {
+      process.stderr.write(
+        `[agentmemory] session/start returned ${res.status} for ${sessionId}\n`,
+      );
     }
   } catch {
-    // silently fail -- don't block Claude Code startup
+    // network/timeout — don't block Claude Code startup; observe-side
+    // will still pick up the session via auto-upsert (#522).
   }
 }