diff --git a/package.json b/package.json
index 9df0b8c..b4a6297 100644
--- a/package.json
+++ b/package.json
@@ -15,8 +15,9 @@
     "dev": "tsx src/index.ts",
     "start": "node dist/index.js",
     "typecheck:tests": "tsc --noEmit -p tsconfig.test.json",
-    "test": "NATEMPLATE_STUB_PLANNER=1 node --import tsx --test tests/smoke.test.ts",
-    "ci": "npm run build && npm run typecheck:tests && npm test"
+    "test": "NATEMPLATE_STUB_ALL=1 node --import tsx --test tests/smoke.test.ts",
+    "ci": "npm run build && npm run typecheck:tests && npm test",
+    "cost": "bash scripts/cost.sh"
   },
   "keywords": [],
   "author": "",
diff --git a/scripts/cost.sh b/scripts/cost.sh
new file mode 100755
index 0000000..fa91996
--- /dev/null
+++ b/scripts/cost.sh
@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+#
+# Aggregate token usage from tmp/trace/*.log and estimate Opus 4.7 cost.
+# Each sub-agent emits lines like:
+#   [02:09:29] usage: 1897 in / 656 out
+# This script sums those per agent, prints a table, and estimates USD.
+#
+# Usage: scripts/cost.sh   (or: npm run cost)
+# Opus 4.7 rates: $15/Mtok input, $75/Mtok output.
+
+set -euo pipefail
+
+trace_dir="$(cd "$(dirname "$0")/.." && pwd)/tmp/trace"
+
+if [[ ! -d "$trace_dir" ]] || ! compgen -G "$trace_dir/*.log" >/dev/null; then
+  echo "no trace files at $trace_dir — run \`npm run dev -- \"...\"\` first"
+  exit 0
+fi
+
+awk '
+  BEGIN {
+    printf "%-12s %6s %12s %12s %12s\n", "Agent", "Calls", "Tokens in", "Tokens out", "Est. USD"
+    printf "%-12s %6s %12s %12s %12s\n", "------------", "------", "------------", "------------", "------------"
+  }
+  /usage:/ {
+    agent = FILENAME
+    sub(/.*\//, "", agent)
+    sub(/\.log$/, "", agent)
+    in_tok = 0
+    out_tok = 0
+    for (i = 1; i <= NF; i++) {
+      if ($i == "usage:") { in_tok = $(i + 1); out_tok = $(i + 4) }
+    }
+    if (!(agent in seen)) { order[++n_agents] = agent; seen[agent] = 1 }
+    calls[agent]++
+    sum_in[agent] += in_tok
+    sum_out[agent] += out_tok
+  }
+  END {
+    if (n_agents == 0) {
+      print "no usage: lines found in trace logs"
+      exit 0
+    }
+    total_calls = 0; total_in = 0; total_out = 0; total_cost = 0
+    for (i = 1; i <= n_agents; i++) {
+      a = order[i]
+      cost = sum_in[a] * 15 / 1000000 + sum_out[a] * 75 / 1000000
+      printf "%-12s %6d %12d %12d %12s\n", a, calls[a], sum_in[a], sum_out[a], sprintf("$%.4f", cost)
+      total_calls += calls[a]
+      total_in += sum_in[a]
+      total_out += sum_out[a]
+      total_cost += cost
+    }
+    printf "%-12s %6s %12s %12s %12s\n", "------------", "------", "------------", "------------", "------------"
+    printf "%-12s %6d %12d %12d %12s\n", "Total", total_calls, total_in, total_out, sprintf("$%.4f", total_cost)
+  }
+' "$trace_dir"/*.log
diff --git a/src/agents/planner.ts b/src/agents/planner.ts
index 2e7567f..da1e88d 100644
--- a/src/agents/planner.ts
+++ b/src/agents/planner.ts
@@ -1,5 +1,6 @@
 import Anthropic from "@anthropic-ai/sdk";
 import { trace } from "../trace.js";
+import { isStub } from "../stub.js";
 import type { DomainSpec } from "./types.js";
 
 const MODEL = "claude-opus-4-7";
@@ -83,7 +84,7 @@ const DOMAIN_TOOL: Anthropic.Messages.Tool = {
 export async function runPlanner(spec: string): Promise<DomainSpec> {
   trace("planner", `received spec: "${spec}"`);
 
-  if (process.env['NATEMPLATE_STUB_PLANNER'] === "1") {
+  if (isStub("planner")) {
     return runStubPlanner(spec);
   }
 
@@ -117,7 +118,7 @@ export async function runPlanner(spec: string): Promise<DomainSpec> {
 const delay = (ms: number): Promise<void> => new Promise((r) => { setTimeout(r, ms); });
 
 async function runStubPlanner(spec: string): Promise<DomainSpec> {
-  trace("planner", "(stub mode — NATEMPLATE_STUB_PLANNER=1)");
+  trace("planner", "(stub mode — NATEMPLATE_STUB_ALL or NATEMPLATE_STUB_PLANNER set)");
   await delay(200);
   trace("planner", "extracting entities and fields");
   await delay(250);
diff --git a/src/stub.ts b/src/stub.ts
new file mode 100644
index 0000000..2c538eb
--- /dev/null
+++ b/src/stub.ts
@@ -0,0 +1,6 @@
+import type { AgentName } from "./agents/types.js";
+
+export function isStub(agent: AgentName): boolean {
+  if (process.env['NATEMPLATE_STUB_ALL'] === "1") return true;
+  return process.env[`NATEMPLATE_STUB_${agent.toUpperCase()}`] === "1";
+}