fix(opencode): support OpenCode 2 plugin API (V1/V2 dual export)

package.json

@@ -104,6 +104,7 @@
     "@clack/prompts": "^1.0.1",
     "@mixmark-io/domino": "^2.2.0",
     "@modelcontextprotocol/sdk": "^1.26.0",
+    "@opencode/plugin": "^2.0.4",
     "better-sqlite3": "^12.6.2",
     "picocolors": "^1.1.1",
     "turndown": "^7.2.0",

src/session/extract.ts

@@ -1892,6 +1892,75 @@ export function parseOpencodeUsage(payload: unknown): AgentUsageCounts | null {
   };
 }
 
+/**
+ * Map an OpenCode v2 `session.step.ended` payload into the `buildAgentUsageEvent`
+ * input shape.
+ *
+ * The v2 bus has no `message.updated` event, so the v1 parser is unusable
+ * here. v2 usage lives under `data` (not `properties.info`); the model is NOT
+ * carried on the usage event — it is observed on the matching
+ * `session.step.started` and passed in as `modelId` (the caller correlates
+ * the two events by `assistantMessageID`); and there is an extra `reasoning`
+ * token bucket. Field names verified against the published
+ * @opencode/plugin@2.0.16 + @opencode/schema@2.0.16 types.
+ *
+ * Following the gemini-cli convention (thoughts folded into output), the v2
+ * `reasoning` bucket is folded into `output_tokens` — the provider bills it as
+ * output. The event ships a native USD cost, so it is taken verbatim as
+ * `native_cost_usd` and the pricing catalog is bypassed.
+ *
+ * Pure, null-safe, struct-only — NO regex. Returns null when every token bucket is
+ * zero/absent, so an all-zero step emits no event.
+ */
+export function parseOpencodeV2StepUsage(
+  data: unknown,
+  modelId: string,
+): AgentUsageCounts | null {
+  if (!data || typeof data !== "object") return null;
+  const d = data as Record<string, unknown>;
+
+  const tokensRaw = d.tokens;
+  if (!tokensRaw || typeof tokensRaw !== "object") return null;
+  const tokens = tokensRaw as Record<string, unknown>;
+
+  const num = (v: unknown): number =>
+    typeof v === "number" && Number.isFinite(v) && v > 0 ? v : 0;
+
+  const cacheRaw = tokens.cache;
+  const cache =
+    cacheRaw && typeof cacheRaw === "object"
+      ? (cacheRaw as Record<string, unknown>)
+      : {};
+
+  const input_tokens = num(tokens.input);
+  // v2 exposes a distinct `reasoning` bucket; fold it into output (billed as output).
+  const output_tokens = num(tokens.output) + num(tokens.reasoning);
+  const cache_read_tokens = num(cache.read);
+  const cache_creation_tokens = num(cache.write);
+
+  if (
+    input_tokens <= 0 &&
+    output_tokens <= 0 &&
+    cache_creation_tokens <= 0 &&
+    cache_read_tokens <= 0
+  ) {
+    return null;
+  }
+
+  const costRaw = d.cost;
+  const native_cost_usd =
+    typeof costRaw === "number" && Number.isFinite(costRaw) ? costRaw : null;
+
+  return {
+    model_id: typeof modelId === "string" ? modelId : "",
+    input_tokens,
+    output_tokens,
+    cache_creation_tokens,
+    cache_read_tokens,
+    native_cost_usd,
+  };
+}
+
 /**
  * Build a structured `agent_usage` event from summed per-model token counts.
  * Emits the colon-string `data` (human/debug + back-compat) AND the structured