Merge compact-tool-pairing into token-meter-service

# Conflicts:
#	docs/event-producer-consumer.md

packages/core/agent-loop/src/loop.ts

@@ -574,7 +574,8 @@ async function runStep(
     })
     session.append('tool/result', {
       turn, step,
-      // Preserve transcript pairing even if a post-execute listener returns another id.
+      // Correlation comes from the immutable execution input; the result does
+      // not duplicate this authoritative transcript identity.
       callId: call.id,
       content: result.content,
       isError: result.isError,

packages/core/agent-loop/tests/contract-regressions.spec.ts

@@ -1109,8 +1109,7 @@ describe('tool result call identity', () => {
 
     // A post-execute listener transforms the result (accept-with-replacement).
     // The loop must still record the tool/result under the model's authoritative
-    // call.id (the loop ignores result.callId — which the registry always sets to
-    // exec.callId anyway — and uses call.id, the model-transcript id).
+    // call.id, which is the immutable identity carried by the execution input.
     ctx.on('tools/post-execute', (exec, _result) => {
       expect(exec.callId).toBe(CallId('c1')) // the loop passed the real id in
       return Promise.resolve({ kind: 'accept', content: [{ type: 'text', text: 'ok' }] })
@@ -1120,8 +1119,7 @@ describe('tool result call identity', () => {
     send(agent, 'use tool')
     await waitForIdle(ctx, agent)
 
-    // The logged tool/result.callId is the originating call.id, NOT the
-    // listener's wrong id.
+    // The logged tool/result.callId is the originating call.id.
     const resultEvent = [...agent.session.events].find(e => e.type === 'tool/result')
     expect(resultEvent?.type).toBe('tool/result')
     if (resultEvent?.type === 'tool/result') {