diff --git a/src/main/agent-runtime/cost-writer.ts b/src/main/agent-runtime/cost-writer.ts
index 1e8407c4..21771062 100644
--- a/src/main/agent-runtime/cost-writer.ts
+++ b/src/main/agent-runtime/cost-writer.ts
@@ -1,7 +1,7 @@
-import { calculateCost, type Usage } from "@mariozechner/pi-ai";
+import { calculateCost, type Usage, type Api, type Model } from "@mariozechner/pi-ai";
 import type { AppDatabase } from "@main/database";
 import { getConnectorDefinition } from "@main/connectors";
-import { resolveModel } from "@main/model-resolver";
+import { resolveModel, resolveModelCostFallback } from "@main/model-resolver";
 
 export interface CostWriterDeps {
   db: AppDatabase;
@@ -17,19 +17,10 @@ interface ObserveInput {
   usage: Usage;
 }
 
-/**
- * Writes a `cost_entries` row for each pi `message_end`. finishRun reads
- * SUM(cost_entries.amount_usd) for the run-level aggregate, so this is
- * the single source of truth for cost attribution.
- */
 export class CostWriter {
   constructor(private readonly deps: CostWriterDeps) {}
 
   observeAssistantMessage(input: ObserveInput): void {
-    // Fail closed on cost calculation — budget policies read `cost_entries`
-    // to enforce spending gates; silently emitting an unattributed row
-    // would let an agent run unbounded. If pricing cannot be resolved,
-    // throw so the caller logs and the missing cost is visible.
     const definition = getConnectorDefinition(input.connectorId);
     if (!definition.provider) {
       throw new Error(`[cost-writer] connector ${input.connectorId} has no provider mapping`);
@@ -38,7 +29,8 @@ export class CostWriter {
     if (!model) {
       throw new Error(`[cost-writer] model ${input.modelId} not found for provider ${definition.provider}`);
     }
-    const cost = calculateCost(model, input.usage);
+    const patchedModel = resolveModelCostFallback(model, definition.provider);
+    const cost = calculateCost(patchedModel, input.usage);
     if (!Number.isFinite(cost.total)) {
       throw new Error(
         `[cost-writer] cost calculation returned non-finite total for ${input.connectorId}/${input.modelId}`,
diff --git a/src/main/model-resolver.ts b/src/main/model-resolver.ts
index be873cdb..8daa88b3 100644
--- a/src/main/model-resolver.ts
+++ b/src/main/model-resolver.ts
@@ -94,6 +94,49 @@ export function resolveModel(provider: string, modelId: string): Model<Api> | nu
   }
 }
 
+const CROSS_PROVIDER_COST_LOOKUP: Record<string, string[]> = {
+  "github-copilot": ["anthropic", "openai", "google", "xai"],
+  "google-gemini-cli": ["google"],
+};
+
+const PROVIDER_FALLBACK_COST: Record<string, { input: number; output: number }> = {
+  "zai": { input: 1, output: 3.2 },
+  "kimi-coding": { input: 0.6, output: 3 },
+};
+
+function normalizeModelId(id: string): string {
+  return id.replace(/\./g, "-");
+}
+
+export function resolveModelCostFallback(model: Model<Api>, provider: string): Model<Api> {
+  if (model.cost.input > 0 || model.cost.output > 0) return model;
+
+  const crossProviders = CROSS_PROVIDER_COST_LOOKUP[provider];
+  if (crossProviders) {
+    const normalized = normalizeModelId(model.id);
+    for (const cp of crossProviders) {
+      try {
+        const sourceModels = getModels(cp as Parameters<typeof getModels>[0]);
+        const match = sourceModels.find((m) => m.id === model.id)
+          ?? sourceModels.find((m) => normalizeModelId(m.id) === normalized)
+          ?? sourceModels.find((m) => normalized.includes(normalizeModelId(m.id)) || normalizeModelId(m.id).includes(normalized));
+        if (match && (match.cost.input > 0 || match.cost.output > 0)) {
+          return { ...model, cost: { ...match.cost } };
+        }
+      } catch {
+        continue;
+      }
+    }
+  }
+
+  const fallback = PROVIDER_FALLBACK_COST[provider];
+  if (fallback) {
+    return { ...model, cost: { ...model.cost, input: fallback.input, output: fallback.output } };
+  }
+
+  return model;
+}
+
 export function resolveModels(provider: string): Array<{ id: string; name: string }> {
   if (provider === "fireworks-firepass") {
     return [{ id: FIREWORKS_FIREPASS_MODEL_ID, name: FIREWORKS_FIREPASS_MODEL_NAME }];