fix(pi): add get_session_stats fallback from get_state for old OMP binaries (#1886)

* fix(pi): add get_session_stats fallback from get_state for old OMP binaries

Older Oh My Pi binaries don't support the get_session_stats RPC command,
leaving session usage stats blank in Paseo. This adds a compat layer in
cli-runtime.ts where getSessionStats() tries get_session_stats first, then
falls back to extracting context window usage from get_state.

The fallback provides contextUsage.tokens and contextWindow even when the
binary lacks full token/cost reporting — enough to keep the context meter
working. Token counts and cost still require the newer RPC.

Added three tests:
- Fallback triggers when get_session_stats is unsupported (throws)
- No fallback when get_session_stats returns valid data
- Returns empty object when both commands fail

* fix(pi): use nullish check instead of truthy for cost field in getSessionStats

packages/server/src/server/agent/providers/pi/cli-runtime.test.ts

@@ -61,16 +61,29 @@ function replyToCommands(
       const line = buffer.slice(0, newlineIndex);
       buffer = buffer.slice(newlineIndex + 1);
       const command = JSON.parse(line) as Record<string, unknown>;
-      const result = handler(command);
-      child.stdout.write(
-        `${JSON.stringify({
-          id: command.id,
-          type: "response",
-          command: command.type,
-          success: true,
-          data: result,
-        })}\n`,
-      );
+      try {
+        const result = handler(command);
+        child.stdout.write(
+          `${JSON.stringify({
+            id: command.id,
+            type: "response",
+            command: command.type,
+            success: true,
+            data: result,
+          })}\n`,
+        );
+      } catch (error) {
+        const message = error instanceof Error ? error.message : String(error);
+        child.stdout.write(
+          `${JSON.stringify({
+            id: command.id,
+            type: "response",
+            command: command.type,
+            success: false,
+            error: message,
+          })}\n`,
+        );
+      }
     }
   });
 }
@@ -257,4 +270,102 @@ describe("PiCliRuntime", () => {
 
     expect(child.killedSignals).toContain("SIGTERM");
   });
+
+  test("falls back to get_state when get_session_stats is unsupported", async () => {
+    const child = createPiChild();
+    let commandSequence: string[] = [];
+    replyToCommands(child, (command) => {
+      commandSequence.push(String(command.type));
+      if (command.type === "get_session_stats") {
+        // Simulate older OMP binary that doesn't support this RPC
+        throw new Error(`Unknown command: ${command.type}`);
+      }
+      // get_state returns contextUsage for fallback
+      return {
+        sessionId: "pi-session-1",
+        thinkingLevel: "medium" as const,
+        isStreaming: false,
+        isCompacting: false,
+        steeringMode: "one-at-a-time" as const,
+        followUpMode: "one-at-a-time" as const,
+        interruptMode: "immediate" as const,
+        messageCount: 0,
+        queuedMessageCount: 0,
+        todoPhases: [],
+        contextUsage: { tokens: 1_100, contextWindow: 200_000 },
+      };
+    });
+    const session = await createRuntime(child).startSession({ cwd: "/workspace/project" });
+
+    const stats = await session.getSessionStats();
+
+    expect(stats.contextUsage).toEqual({
+      tokens: 1_100,
+      contextWindow: 200_000,
+    });
+    expect(commandSequence).toEqual(["get_session_stats", "get_state"]);
+  });
+
+  test("returns full stats from get_session_stats without falling back", async () => {
+    const child = createPiChild();
+    let fallbackCalled = false;
+    replyToCommands(child, (command) => {
+      if (command.type === "get_state") {
+        fallbackCalled = true;
+      }
+      return {
+        tokens: { input: 500, output: 300, cacheRead: 100 },
+        cost: 0.02,
+        contextUsage: { tokens: 800, contextWindow: 200_000 },
+      };
+    });
+    const session = await createRuntime(child).startSession({ cwd: "/workspace/project" });
+
+    const stats = await session.getSessionStats();
+
+    expect(stats).toMatchObject({
+      tokens: { input: 500, output: 300, cacheRead: 100 },
+      cost: 0.02,
+      contextUsage: { tokens: 800, contextWindow: 200_000 },
+    });
+    // Should NOT have called get_state as a fallback
+    expect(fallbackCalled).toBe(false);
+  });
+
+  test("does not fall back when get_session_stats returns cost:0", async () => {
+    const child = createPiChild();
+    let fallbackCalled = false;
+    replyToCommands(child, (command) => {
+      if (command.type === "get_state") {
+        fallbackCalled = true;
+      }
+      return {
+        tokens: { input: 200, output: 100 },
+        cost: 0,
+        contextUsage: { tokens: 500, contextWindow: 200_000 },
+      };
+    });
+    const session = await createRuntime(child).startSession({ cwd: "/workspace/project" });
+
+    const stats = await session.getSessionStats();
+
+    expect(stats.tokens).toEqual({ input: 200, output: 100 });
+    expect(stats.cost).toBe(0);
+    expect(stats.contextUsage).toEqual({ tokens: 500, contextWindow: 200_000 });
+    // Should NOT have called get_state as a fallback
+    expect(fallbackCalled).toBe(false);
+  });
+
+  test("returns empty object when both get_session_stats and get_state fail", async () => {
+    const child = createPiChild();
+    replyToCommands(child, (command) => {
+      throw new Error(`Unknown command: ${command.type}`);
+    });
+    const session = await createRuntime(child).startSession({ cwd: "/workspace/project" });
+
+    const stats = await session.getSessionStats();
+
+    // Neither RPC returned usable data — should resolve with empty object
+    expect(stats).toEqual({});
+  });
 });

packages/server/src/server/agent/providers/pi/cli-runtime.ts

@@ -180,7 +180,35 @@ class PiCliRuntimeSession implements PiRuntimeSession {
   }
 
   async getSessionStats(): Promise<PiSessionStats> {
-    return (await this.request({ type: "get_session_stats" })) as PiSessionStats;
+    // COMPAT(piGetStateFallback): added in v0.1.X — older Oh My Pi binaries
+    // lack the `get_session_stats` RPC command; fall back to extracting
+    // context window usage from `get_state`. Drop this gate when the floor
+    // daemon supports get_session_stats (added ~v0.1.97).
+    let stats: PiSessionStats | undefined;
+    try {
+      stats = (await this.request({ type: "get_session_stats" })) as PiSessionStats;
+    } catch {
+      // get_session_stats not supported by this binary — will try get_state below
+    }
+    if (stats?.tokens == null && stats?.cost == null && stats?.contextUsage == null) {
+      try {
+        const state = (await this.request({ type: "get_state" })) as Record<string, unknown>;
+        const ctx = state.contextUsage as
+          | { tokens?: number | null; contextWindow?: number | null }
+          | undefined;
+        if (ctx) {
+          return {
+            contextUsage: {
+              tokens: typeof ctx.tokens === "number" ? ctx.tokens : undefined,
+              contextWindow: typeof ctx.contextWindow === "number" ? ctx.contextWindow : undefined,
+            },
+          };
+        }
+      } catch {
+        // get_state also failed — nothing we can do
+      }
+    }
+    return stats ?? {};
   }
 
   async getCommands(): Promise<PiRpcSlashCommand[]> {