Reset the context meter on clear and after compaction

src/agent/compaction.test.ts

@@ -103,8 +103,8 @@ describe("compaction governor", () => {
     expect(actions?.some((a) => a.type === "infer")).toBe(false);
     expect(continuations).toBe(1);
 
-    expect(governor.resumeAfterCompact(emptyMessage())).toBe(true);
-    expect(governor.resumeAfterCompact(emptyMessage())).toBe(false);
+    expect(governor.resumeAfterCompact(emptyMessage())).toBe("infer");
+    expect(governor.resumeAfterCompact(emptyMessage())).toBeNull();
   });
 
   test("stays inert below the threshold or with few turns", () => {
@@ -134,7 +134,7 @@ describe("compaction governor", () => {
   test("recovers from context overflow a bounded number of times", () => {
     const governor = createCompactionGovernor(() => {});
     expect(governor.interceptOverflow(overflowError(), capabilities)).not.toBeNull();
-    expect(governor.resumeAfterCompact(emptyMessage())).toBe(true);
+    expect(governor.resumeAfterCompact(emptyMessage())).toBe("infer");
     expect(governor.interceptOverflow(overflowError(), capabilities)).not.toBeNull();
     expect(governor.interceptOverflow(overflowError(), capabilities)).toBeNull();
 
@@ -162,6 +162,38 @@ describe("compaction governor", () => {
     expect(governor.interceptIdleContinuation(emptyMessage(), capabilities)).toBeNull();
   });
 
+  // Idle compact with an empty continuation previously left postCompactInfer
+  // unset, so resumeAfterCompact never fired and notePostCompact never ran —
+  // the Ctx meter stayed on pre-compact lastTurnUsage until the next user turn.
+  test("idle empty compact syncs the meter after shrink without a following user turn", () => {
+    let continuations = 0;
+    const governor = createCompactionGovernor(() => continuations++);
+    const large = turnsOfLength(10, 200);
+    governor.noteInferenceDone(inferenceDone(overThreshold), large);
+    expect(governor.usingEstimate).toBe(false);
+    const before = governor.estimatedTokens;
+
+    governor.noteIdleTurn(inferenceDone(overThreshold), [{ type: "reply", content: "done" }]);
+    expect(continuations).toBe(1);
+
+    const actions = governor.interceptIdleContinuation(emptyMessage(), capabilities);
+    expect(actions).toEqual([
+      { type: "compact", compactor: "pruning-compactor", reason: "context-threshold" },
+    ] as ReactorAction[]);
+    // A second continuation re-enters decide after the compact cycle so the
+    // governor can adopt the shrunk turns — without starting a new inference.
+    expect(continuations).toBe(2);
+
+    const shrunk = turnsOfLength(3, 20);
+    // resumeAfterCompact must arm the meter-only path (not infer) for empty idle.
+    expect(governor.resumeAfterCompact(emptyMessage())).toBe("meter");
+    governor.notePostCompact(shrunk);
+
+    expect(governor.usingEstimate).toBe(true);
+    expect(governor.estimatedTokens).toBeLessThan(before);
+    expect(governor.estimatedTokens).toBe(governor.syncFromTurns(shrunk));
+  });
+
   test("an operator message that races the idle continuation still compacts, then re-infers", () => {
     let continuations = 0;
     const governor = createCompactionGovernor(() => continuations++);
@@ -177,7 +209,7 @@ describe("compaction governor", () => {
     // A second continuation is requested so the operator message gets answered
     // after the compact cycle.
     expect(continuations).toBe(2);
-    expect(governor.resumeAfterCompact(emptyMessage())).toBe(true);
+    expect(governor.resumeAfterCompact(emptyMessage())).toBe("infer");
   });
 
   test("idle turns with follow-up work or under threshold never arm idle compaction", () => {
@@ -337,6 +369,25 @@ describe("compaction governor", () => {
     expect(governor.interceptActions(toolDone(), inferAction, capabilities)).toBeNull();
   });
 
+  test("notePostCompact syncs the shrunk turns and keeps the estimate authoritative until the next inference.done", () => {
+    const governor = createCompactionGovernor(() => {});
+    const large = turnsOfLength(10, 200);
+    governor.noteInferenceDone(inferenceDone(overThreshold), large);
+    expect(governor.usingEstimate).toBe(false);
+    const before = governor.estimatedTokens;
+
+    const shrunk = turnsOfLength(3, 20);
+    governor.notePostCompact(shrunk);
+
+    expect(governor.usingEstimate).toBe(true);
+    expect(governor.estimatedTokens).toBeLessThan(before);
+    expect(governor.estimatedTokens).toBe(governor.syncFromTurns(shrunk));
+
+    // Provider-reported usage on the next turn clears the estimate flag.
+    governor.noteInferenceDone(inferenceDone(1000), shrunk);
+    expect(governor.usingEstimate).toBe(false);
+  });
+
   test("does not re-arm after a compact that remains over the high watermark", () => {
     const governor = createCompactionGovernor(() => {});
     governor.noteInferenceDone(inferenceDone(overThreshold), tenTurns);

src/agent/compaction.ts

@@ -40,6 +40,10 @@ export function createCompactionGovernor(
   let pending = false;
   let idlePending = false;
   let postCompactInfer = false;
+  // Idle empty compact needs a post-compact decide cycle to adopt the shrunk
+  // turns for the meter, but must not start a new inference (there is no
+  // operator question to answer). Distinct from postCompactInfer.
+  let postCompactMeter = false;
   let overflowRecoveries = 0;
   // Set whenever the arming decision fell back to the local estimate because
   // the provider omitted usage or reported zero, so callers rendering a meter
@@ -167,13 +171,17 @@ export function createCompactionGovernor(
     idlePending = false;
     pending = false;
     const content = typeof event.message.content === "string" ? event.message.content : "";
-    // An operator message that raced the continuation is already in history;
-    // compact first, then request another continuation to answer it.
+    // The reactor delivers no event after compact, so always request a
+    // continuation to re-enter decide against the shrunk turns:
+    // - raced operator content → re-infer to answer it
+    // - empty synthetic continuation → meter-only sync (no infer)
     if (content.length > 0) {
       postCompactInfer = true;
-      requestContinuation?.();
+    } else {
+      postCompactMeter = true;
     }
     noteCompactIssued();
+    requestContinuation?.();
     return [capabilities.compact(COMPACTOR_NAME, "context-threshold")];
   }
 
@@ -197,12 +205,30 @@ export function createCompactionGovernor(
     return [capabilities.compact(COMPACTOR_NAME, "context-overflow")];
   }
 
-  function resumeAfterCompact(event: ReactorInboundEvent): boolean {
-    if (!postCompactInfer || event.type !== "message.received") return false;
+  // After compact, a content-less continuation re-enters decide. "infer" means
+  // resume the interrupted loop; "meter" means adopt the shrunk turns for the
+  // Ctx display and stay idle (idle empty compact has nothing to answer).
+  function resumeAfterCompact(event: ReactorInboundEvent): "infer" | "meter" | null {
+    if (event.type !== "message.received") return null;
     const content = typeof event.message.content === "string" ? event.message.content : "";
-    if (content.length > 0) return false;
-    postCompactInfer = false;
-    return true;
+    if (content.length > 0) return null;
+    if (postCompactInfer) {
+      postCompactInfer = false;
+      return "infer";
+    }
+    if (postCompactMeter) {
+      postCompactMeter = false;
+      return "meter";
+    }
+    return null;
+  }
+
+  // After a successful compact, the provider-reported usage from before the
+  // shrink is stale. Re-sync from the compacted turns and treat the local
+  // estimate as authoritative until the next real inference.done.
+  function notePostCompact(turns: readonly ConversationTurn[]): void {
+    syncFromTurns(turns);
+    usingEstimate = true;
   }
 
   return {
@@ -217,6 +243,7 @@ export function createCompactionGovernor(
     },
     syncFromTurns,
     noteInferenceDone,
+    notePostCompact,
     noteIdleTurn,
     interceptActions,
     interceptIdleContinuation,

src/agent/director.ts

@@ -651,7 +651,14 @@ class ChatDirectorImpl extends DefaultDirector {
     state: ReactorState,
     capabilities: ReactorCapabilities,
   ): Promise<ReactorAction | ReactorAction[]> {
-    if (this.compaction.resumeAfterCompact(event)) {
+    const afterCompact = this.compaction.resumeAfterCompact(event);
+    if (afterCompact !== null) {
+      // Compacted history is the live occupancy until the next provider-
+      // reported inference.done; paint from the estimate in the meantime.
+      this.compaction.notePostCompact(state.turns ?? []);
+      // Idle empty compact only needed the decide re-entry to sync the meter;
+      // stay idle rather than starting an unprompted inference.
+      if (afterCompact === "meter") return capabilities.wait();
       return capabilities.infer();
     }
     const idleCompact = this.compaction.interceptIdleContinuation(event, capabilities);

src/cost/cost-summary.test.ts

@@ -5,6 +5,7 @@ import {
   buildCostSummary,
   formatCostCommandOutput,
   formatStatusBarSegments,
+  maskContextMeterWhenNoTurns,
 } from "./cost-summary.js";
 import type { CostSummaryInput } from "./cost-summary.js";
 
@@ -64,6 +65,25 @@ describe("buildCostSummary", () => {
   });
 });
 
+describe("maskContextMeterWhenNoTurns", () => {
+  it("hides the meter on a zero-turn session even when contextTokens are non-zero", () => {
+    const summary = buildCostSummary(baseInput);
+    expect(summary.contextPercentUsed).toBe(50);
+
+    const masked = maskContextMeterWhenNoTurns(summary, 0);
+    expect(masked.contextPercentUsed).toBeNull();
+    expect(masked.contextIsEstimate).toBe(false);
+    // Cost totals stay untouched — only occupancy display is suppressed.
+    expect(masked.totalCost).toBe(summary.totalCost);
+    expect(masked.formattedCost).toBe(summary.formattedCost);
+  });
+
+  it("leaves a session with turns unchanged", () => {
+    const summary = buildCostSummary(baseInput);
+    expect(maskContextMeterWhenNoTurns(summary, 1)).toEqual(summary);
+  });
+});
+
 describe("formatStatusBarSegments", () => {
   it("includes both cost and context when cost is not hidden", () => {
     const summary = buildCostSummary(baseInput);

src/cost/cost-summary.ts

@@ -53,6 +53,15 @@ export function buildCostSummary(input: CostSummaryInput): CostSummary {
   };
 }
 
+// Zero-turn sessions (fresh launch, post-/clear, post-/new) have no occupancy
+// to report. Hide the meter rather than showing 0% or the new director's
+// system-prompt/tool-schema overhead as if it were live usage. Cost totals
+// stay untouched.
+export function maskContextMeterWhenNoTurns(summary: CostSummary, turnCount: number): CostSummary {
+  if (turnCount > 0) return summary;
+  return { ...summary, contextPercentUsed: null, contextIsEstimate: false };
+}
+
 export interface StatusBarCostSegments {
   costLabel?: string;
   contextLabel: string;

src/director.test.ts

@@ -363,6 +363,44 @@ describe("chatDirector compaction", () => {
     expect(compactActions).toEqual([
       { type: "compact", compactor: "pruning-compactor", reason: "context-threshold" },
     ]);
+    // Idle empty compact schedules a second continuation so decide can adopt
+    // the shrunk turns for the meter without starting a new inference.
+    expect(continuations).toBe(2);
+  });
+
+  test("idle empty compact makes the post-compact estimate authoritative without inferring", async () => {
+    const director = createChatDirector("", [], {
+      onTasksChange: () => {},
+      requestContinuation: () => {},
+    });
+    const largeTurns = Array.from(
+      { length: compactorNoOpFloor(COMPACTOR_KEEP_RECENT_TURNS) + 1 },
+      (_, i) => ({
+        role: i % 2 === 0 ? "user" : "assistant",
+        content: [{ type: "text", text: "x".repeat(200) }],
+        timestamp: i,
+      }),
+    );
+    const longState = { turns: largeTurns } as unknown as ReactorState;
+
+    await director.decide(textInferenceDone(999_999), longState, mockCapabilities);
+    expect(director.getContextEstimate().isEstimate).toBe(false);
+    const before = director.getContextEstimate().tokens;
+
+    await director.decide(messageReceived(""), longState, mockCapabilities);
+
+    // Simulate the reactor having compacted, then the meter-sync continuation.
+    const shrunkTurns = largeTurns.slice(-3);
+    const shrunkState = { turns: shrunkTurns } as unknown as ReactorState;
+    const afterActions = actionsArray(
+      await director.decide(messageReceived(""), shrunkState, mockCapabilities),
+    );
+    expect(afterActions.some((a) => a.type === "infer")).toBe(false);
+    expect(afterActions.some((a) => a.type === "wait" || a.type === "reply")).toBe(true);
+
+    const estimate = director.getContextEstimate();
+    expect(estimate.isEstimate).toBe(true);
+    expect(estimate.tokens).toBeLessThan(before);
   });
 
   // One turn past createPruningCompactor's own no-op floor (session/compactor.ts).

src/subagent/nudge-director.ts

@@ -179,7 +179,14 @@ export class SubAgentDirector extends DefaultDirector {
     state: ReactorState,
     capabilities: ReactorCapabilities,
   ): Promise<ReactorAction | ReactorAction[]> {
-    if (this.compaction.resumeAfterCompact(event)) {
+    const afterCompact = this.compaction.resumeAfterCompact(event);
+    if (afterCompact !== null) {
+      // Compacted history is the live occupancy until the next provider-
+      // reported inference.done; paint from the estimate in the meantime.
+      this.compaction.notePostCompact(state.turns ?? []);
+      // Idle empty compact only needed the decide re-entry to sync the meter;
+      // stay idle rather than starting an unprompted inference.
+      if (afterCompact === "meter") return capabilities.wait();
       return this.applyPendingNudge([capabilities.infer()], capabilities);
     }
     const idleCompact = this.compaction.interceptIdleContinuation(event, capabilities);