fix(cost): per-model pricing so pi/Paperclip report real spend

The omni provider's models.json entries carried no 'cost' field, so pi's
calculateCost() returned 0 for every run and Paperclip cost events/budgets
all read $0.00 despite real spend.

- scripts/omni-pricing.mjs: pulls authoritative prices (OmniRoute /api/pricing
  for deepseek/*, OpenRouter /api/v1/models for openrouter/*) and injects
  { cost: { input, output, cacheRead, cacheWrite } } USD per 1M tokens.
- Priced: deepseek-v4-flash, deepseek-v4-pro, gemini-3.1-flash-lite, gemini-2.5-flash.
- Must be re-run after every /omni sync, which rewrites models.json wholesale.

scripts/omni-pricing.mjs

@@ -0,0 +1,164 @@
+#!/usr/bin/env node
+/**
+ * Inject per-model pricing into ~/.agents/models.json for the `omni` provider.
+ *
+ * WHY THIS EXISTS
+ * ---------------
+ * `pi --list-models` / the omni extension's /omni sync regenerates models.json
+ * from OmniRoute and writes entries WITHOUT a `cost` field. pi's calculateCost()
+ * then reports $0.00 for every run, so Paperclip's cost events and budgets all
+ * read zero even though real money is being spent.
+ *
+ * The fix is to add { cost: { input, output, cacheRead, cacheWrite } } (USD per
+ * million tokens) to the model entries we actually use.
+ *
+ * Because /omni sync rewrites the whole file, this script must be re-run after
+ * every sync. That is the whole reason it is a script and not a one-off edit.
+ *
+ * PRICE SOURCES (both authoritative, no guessing)
+ *   - deepseek/*      -> OmniRoute /api/pricing, group "deepseek"
+ *   - openrouter/*    -> OpenRouter /api/v1/models (strip the "openrouter/" prefix)
+ *
+ * Model ids that use routing prefixes (aug/, ds/, oc/, tllm/, opencode-go/) do
+ * NOT map cleanly to pricing groups and are deliberately skipped — add them to
+ * MANUAL below if you need them.
+ *
+ * USAGE
+ *   node omni-pricing.mjs --dry-run     # show what would change
+ *   node omni-pricing.mjs               # write models.json
+ */
+
+import fs from "node:fs";
+import path from "node:path";
+
+const MODELS_JSON = path.join(process.env.HOME, ".agents", "models.json");
+const OMNIROUTE_PRICING = "http://192.168.20.13:20128/api/pricing";
+const OPENROUTER_MODELS = "https://openrouter.ai/api/v1/models";
+
+// Models we actually assign to workers. Keep this list short and deliberate.
+const TARGETS = [
+  "deepseek/deepseek-v4-flash",
+  "deepseek/deepseek-v4-pro",
+  "openrouter/google/gemini-3.1-flash-lite",
+  "openrouter/google/gemini-2.5-flash",
+];
+
+// Hand-priced entries: id -> {input, output, cacheRead, cacheWrite}
+const MANUAL = {};
+
+const dryRun = process.argv.includes("--dry-run");
+
+function omniKey() {
+  const cfg = JSON.parse(fs.readFileSync(MODELS_JSON, "utf8"));
+  return cfg.providers?.omni?.apiKey ?? "";
+}
+
+/** Fetch OmniRoute's own price table: { group: { model: {input,output,cached,cache_creation} } } */
+async function fetchOmniRoutePricing() {
+  const res = await fetch(OMNIROUTE_PRICING, {
+    headers: { Authorization: `Bearer ${omniKey()}` },
+  });
+  if (!res.ok) throw new Error(`OmniRoute pricing HTTP ${res.status}`);
+  return res.json();
+}
+
+/** Fetch OpenRouter prices keyed by bare model id (no "openrouter/" prefix). */
+async function fetchOpenRouterPricing() {
+  const res = await fetch(OPENROUTER_MODELS);
+  if (!res.ok) throw new Error(`OpenRouter models HTTP ${res.status}`);
+  const { data } = await res.json();
+  const out = {};
+  for (const m of data) {
+    const p = m.pricing ?? {};
+    out[m.id] = {
+      input: Number(p.prompt ?? 0) * 1e6,
+      output: Number(p.completion ?? 0) * 1e6,
+      cacheRead: Number(p.input_cache_read ?? 0) * 1e6,
+      cacheWrite: Number(p.input_cache_write ?? 0) * 1e6,
+    };
+  }
+  return out;
+}
+
+const r6 = (n) => Math.round(Number(n) * 1e6) / 1e6;
+
+/** Resolve a pi model id to a {input,output,cacheRead,cacheWrite} price, or null. */
+function resolvePrice(id, omniPricing, orPricing) {
+  if (MANUAL[id]) return MANUAL[id];
+
+  // deepseek/<name> -> OmniRoute group "deepseek"
+  if (id.startsWith("deepseek/")) {
+    const name = id.slice("deepseek/".length);
+    const row = omniPricing?.deepseek?.[name];
+    if (row) {
+      return {
+        input: r6(row.input),
+        output: r6(row.output),
+        cacheRead: r6(row.cached ?? 0),
+        cacheWrite: r6(row.cache_creation ?? 0),
+      };
+    }
+  }
+
+  // openrouter/<bare-id> -> OpenRouter catalogue
+  if (id.startsWith("openrouter/")) {
+    const bare = id.slice("openrouter/".length);
+    if (orPricing[bare]) {
+      const p = orPricing[bare];
+      return { input: r6(p.input), output: r6(p.output), cacheRead: r6(p.cacheRead), cacheWrite: r6(p.cacheWrite) };
+    }
+  }
+
+  return null;
+}
+
+const cfg = JSON.parse(fs.readFileSync(MODELS_JSON, "utf8"));
+const models = cfg.providers?.omni?.models;
+if (!Array.isArray(models)) {
+  console.error("models.json: providers.omni.models is not an array — aborting");
+  process.exit(1);
+}
+
+const [omniPricing, orPricing] = await Promise.all([
+  fetchOmniRoutePricing(),
+  fetchOpenRouterPricing(),
+]);
+
+const byId = new Map(models.filter((m) => m && m.id).map((m) => [m.id, m]));
+let changed = 0;
+const missing = [];
+
+for (const id of TARGETS) {
+  const entry = byId.get(id);
+  if (!entry) {
+    missing.push(id);
+    continue;
+  }
+  const price = resolvePrice(id, omniPricing, orPricing);
+  if (!price) {
+    missing.push(id);
+    continue;
+  }
+  const current = JSON.stringify(entry.cost ?? null);
+  const next = JSON.stringify(price);
+  if (current !== next) {
+    entry.cost = price;
+    changed++;
+    console.log(
+      `${dryRun ? "[dry-run] " : ""}${id}  ->  in $${price.input}  out $${price.output}  cacheR $${price.cacheRead}  cacheW $${price.cacheWrite}`,
+    );
+  } else {
+    console.log(`${id}  ->  already priced, unchanged`);
+  }
+}
+
+if (missing.length) console.log(`\nnot found / no price (skipped): ${missing.join(", ")}`);
+
+if (dryRun) {
+  console.log(`\ndry-run: ${changed} entr(y/ies) would change`);
+} else if (changed) {
+  fs.writeFileSync(MODELS_JSON, JSON.stringify(cfg, null, 2) + "\n");
+  console.log(`\nwrote ${MODELS_JSON} (${changed} changed)`);
+} else {
+  console.log("\nnothing to do");
+}