feat(llm): add replay token metering (PR2 round 1)

scripts/gen-doc-graphs.ts

@@ -84,6 +84,14 @@ const SERVICE_ROLES: ServiceRole[] = [
     consumers: ['agent-loop', 'compact-basic'],
     note: 'Adapters register provider implementations; the loop and compaction call the provider-neutral stream service.',
   },
+  {
+    key: 'tokenMeter',
+    pkg: 'token-meter',
+    title: 'Replay token measurement',
+    mode: 'core',
+    consumers: ['compact-basic'],
+    note: 'Owns isolated per-model/session replay folds; pressure consumers share immutable revisioned measurements.',
+  },
   {
     key: 'sessions',
     pkg: 'session',
@@ -823,6 +831,8 @@ function renderLifecycle(): string {
     `  Driver-->>SDK: ${mermaidCode('agent/status')} idle`,
     '```',
     '',
+    'The `assistant/message` edge records every successful provider call, including content-less and `max-tokens` finishes. Empty content stays out of derived history while the durable anchor retains usage and exact chunk provenance, including an explicit empty source set.',
+    '',
     'SDK users that need replayable transcript data should consume `session/event`; `agent/*` is the live coordination surface for queue/status, prompt interception, request shaping, steering, continuation, and errors.',
     '',
     ...maintenanceFooter(maintenance),