fix: land multi-agent session path fix + regressions (#15103) (#15448)

Co-authored-by: Josh Lehman <josh@martian.engineering>

src/auto-reply/reply/commands-session.ts

@@ -167,6 +167,7 @@ export const handleUsageCommand: CommandHandler = async (params, allowTextComman
       sessionEntry: params.sessionEntry,
       sessionFile: params.sessionEntry?.sessionFile,
       config: params.cfg,
+      agentId: params.agentId,
     });
     const summary = await loadCostUsageSummary({ days: 30, config: params.cfg });
 

src/auto-reply/reply/commands-status.ts

@@ -224,6 +224,7 @@ export async function buildStatusReply(params: {
       verboseDefault: agentDefaults.verboseDefault,
       elevatedDefault: agentDefaults.elevatedDefault,
     },
+    agentId: statusAgentId,
     sessionEntry,
     sessionKey,
     sessionScope,

src/auto-reply/reply/session.ts

@@ -55,12 +55,13 @@ export type SessionInitResult = {
 
 function forkSessionFromParent(params: {
   parentEntry: SessionEntry;
+  agentId: string;
   sessionsDir: string;
 }): { sessionId: string; sessionFile: string } | null {
   const parentSessionFile = resolveSessionFilePath(
     params.parentEntry.sessionId,
     params.parentEntry,
-    { sessionsDir: params.sessionsDir },
+    { agentId: params.agentId, sessionsDir: params.sessionsDir },
   );
   if (!parentSessionFile || !fs.existsSync(parentSessionFile)) {
     return null;
@@ -225,11 +226,7 @@ export async function initSessionState(params: {
     ? evaluateSessionFreshness({ updatedAt: entry.updatedAt, now, policy: resetPolicy }).fresh
     : false;
 
-  // When this is the first user message in a thread, the session entry may already
-  // exist (created by recordInboundSession in prepare.ts), but we should still treat
-  // it as a new session so that thread context (history/starter/fork) is applied.
-  const forceNewForThread = Boolean(ctx.IsFirstThreadTurn) && !resetTriggered;
-  if (!isNewSession && freshEntry && !forceNewForThread) {
+  if (!isNewSession && freshEntry) {
     sessionId = entry.sessionId;
     systemSent = entry.systemSent ?? false;
     abortedLastRun = entry.abortedLastRun ?? false;
@@ -335,6 +332,7 @@ export async function initSessionState(params: {
     );
     const forked = forkSessionFromParent({
       parentEntry: sessionStore[parentSessionKey],
+      agentId,
       sessionsDir: path.dirname(storePath),
     });
     if (forked) {
@@ -358,7 +356,6 @@ export async function initSessionState(params: {
     // Clear stale token metrics from previous session so /status doesn't
     // display the old session's context usage after /new or /reset.
     sessionEntry.totalTokens = undefined;
-    sessionEntry.totalTokensFresh = false;
     sessionEntry.inputTokens = undefined;
     sessionEntry.outputTokens = undefined;
     sessionEntry.contextTokens = undefined;