fix: normalize blank agent session ids

src/agents/command/session.ts

@@ -143,9 +143,10 @@ export function resolveSessionKeyForRequest(opts: {
   const scope = sessionCfg?.scope ?? "per-sender";
   const mainKey = normalizeMainKey(sessionCfg?.mainKey);
   const requestedAgentId = opts.agentId?.trim() ? normalizeAgentId(opts.agentId) : undefined;
+  const requestedSessionId = opts.sessionId?.trim() || undefined;
   const explicitSessionKey =
     opts.sessionKey?.trim() ||
-    (!opts.sessionId
+    (!requestedSessionId
       ? resolveExplicitAgentSessionKey({
           cfg: opts.cfg,
           agentId: requestedAgentId,
@@ -168,23 +169,23 @@ export function resolveSessionKeyForRequest(opts: {
   // by the shared gateway/session resolver helpers instead of whichever store happens to be scanned
   // first.
   if (
-    opts.sessionId &&
+    requestedSessionId &&
     !explicitSessionKey &&
-    (!sessionKey || sessionStore[sessionKey]?.sessionId !== opts.sessionId)
+    (!sessionKey || sessionStore[sessionKey]?.sessionId !== requestedSessionId)
   ) {
     const { matches, primaryStoreMatches, storeByKey } = collectSessionIdMatchesForRequest({
       cfg: opts.cfg,
       sessionStore,
       storePath,
       storeAgentId,
-      sessionId: opts.sessionId,
+      sessionId: requestedSessionId,
       searchOtherAgentStores: requestedAgentId === undefined,
     });
-    const preferredSelection = resolveSessionIdMatchSelection(matches, opts.sessionId);
+    const preferredSelection = resolveSessionIdMatchSelection(matches, requestedSessionId);
     const currentStoreSelection =
       preferredSelection.kind === "selected"
         ? preferredSelection
-        : resolveSessionIdMatchSelection(primaryStoreMatches, opts.sessionId);
+        : resolveSessionIdMatchSelection(primaryStoreMatches, requestedSessionId);
     if (currentStoreSelection.kind === "selected") {
       const preferred = storeByKey.get(currentStoreSelection.sessionKey);
       if (preferred) {
@@ -194,9 +195,9 @@ export function resolveSessionKeyForRequest(opts: {
     }
   }
 
-  if (opts.sessionId && !sessionKey) {
+  if (requestedSessionId && !sessionKey) {
     sessionKey = buildExplicitSessionIdSessionKey({
-      sessionId: opts.sessionId,
+      sessionId: requestedSessionId,
       agentId: opts.agentId,
     });
   }

src/commands/agent/session.test.ts

@@ -126,6 +126,25 @@ describe("resolveSessionKeyForRequest", () => {
     expect(result.storePath).toBe(MYBOT_STORE_PATH);
   });
 
+  it("treats whitespace --session-id as absent when resolving --agent", async () => {
+    setupMainAndMybotStorePaths();
+    mocks.resolveExplicitAgentSessionKey.mockReturnValue("agent:mybot:main");
+    mockStoresByPath({
+      [MYBOT_STORE_PATH]: {
+        "agent:mybot:main": { sessionId: "existing-session-id", updatedAt: 1 },
+      },
+    });
+
+    const result = resolveSessionKeyForRequest({
+      cfg: baseCfg,
+      agentId: "mybot",
+      sessionId: "   ",
+    });
+
+    expect(result.sessionKey).toBe("agent:mybot:main");
+    expect(result.storePath).toBe(MYBOT_STORE_PATH);
+  });
+
   it("does not search other agent stores when --agent scopes --session-id", async () => {
     setupMainAndMybotStorePaths();
     mockStoresByPath({