fix(cli-runner): reseed from raw tail when session has no compaction (#79713)

loadCliSessionReseedMessages returned [] for any session that had never
been compacted, making the historyPrompt fallback silently inert. On
short sessions (the common case for Discord/Telegram DMs), this meant
every CLI invalidation (idle timeout, system-prompt change) restarted
the agent with no prior context.

Return limitAgentHookHistoryMessages(rawTail) instead, mirroring the
same cap already applied to the post-compaction tail messages.  The
rival opt-in config approach (#77583) stalled on a missing CliBackend
schema key; always-on is simpler and matches the issue author's suggested
fix.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/agents/cli-runner/session-history.test.ts

@@ -226,24 +226,28 @@ describe("loadCliSessionReseedMessages", () => {
     vi.unstubAllEnvs();
   });
 
-  it("does not reseed fresh CLI sessions from raw transcript history before compaction", async () => {
+  it("reseeds fresh CLI sessions from raw message tail when no compaction exists", async () => {
     const stateDir = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-cli-state-"));
     vi.stubEnv("OPENCLAW_STATE_DIR", stateDir);
     const sessionFile = createSessionTranscript({
       rootDir: stateDir,
       sessionId: "session-no-compaction",
-      messages: ["raw secret", "large context"],
+      messages: ["first message", "second message"],
     });
 
     try {
-      expect(
-        await loadCliSessionReseedMessages({
-          sessionId: "session-no-compaction",
-          sessionFile,
-          sessionKey: "agent:main:main",
-          agentId: "main",
-        }),
-      ).toStrictEqual([]);
+      const reseed = await loadCliSessionReseedMessages({
+        sessionId: "session-no-compaction",
+        sessionFile,
+        sessionKey: "agent:main:main",
+        agentId: "main",
+      });
+      expect(reseed).toHaveLength(2);
+      expect(reseed[0]).toMatchObject({ role: "user", content: "first message" });
+      expect(reseed[1]).toMatchObject({ role: "user", content: "second message" });
+      expect(buildCliSessionHistoryPrompt({ messages: reseed, prompt: "next" })).toContain(
+        "first message",
+      );
     } finally {
       fs.rmSync(stateDir, { recursive: true, force: true });
     }

src/agents/cli-runner/session-history.ts

@@ -197,7 +197,13 @@ export async function loadCliSessionReseedMessages(params: {
     return candidate.type === "compaction" && typeof candidate.summary === "string";
   });
   if (latestCompactionIndex < 0) {
-    return [];
+    // Session never compacted — return raw message tail so historyPrompt is
+    // not silently inert on short sessions invalidated before compaction (#79713).
+    const rawTail = entries.flatMap((entry) => {
+      const candidate = entry as HistoryEntry;
+      return candidate.type === "message" ? [candidate.message] : [];
+    });
+    return limitAgentHookHistoryMessages(rawTail, MAX_CLI_SESSION_HISTORY_MESSAGES);
   }
 
   const compaction = entries[latestCompactionIndex] as HistoryEntry;