diff --git a/packages/opencode/src/agent/agent.ts b/packages/opencode/src/agent/agent.ts
index 96b71f816bf9..0c6fe6ec91c8 100644
--- a/packages/opencode/src/agent/agent.ts
+++ b/packages/opencode/src/agent/agent.ts
@@ -75,6 +75,7 @@ export namespace Agent {
       const config = yield* Config.Service
       const auth = yield* Auth.Service
       const skill = yield* Skill.Service
+      const provider = yield* Provider.Service
 
       const state = yield* InstanceState.make<State>(
         Effect.fn("Agent.state")(function* (ctx) {
@@ -330,9 +331,9 @@ export namespace Agent {
           model?: { providerID: ProviderID; modelID: ModelID }
         }) {
           const cfg = yield* config.get()
-          const model = input.model ?? (yield* Effect.promise(() => Provider.defaultModel()))
-          const resolved = yield* Effect.promise(() => Provider.getModel(model.providerID, model.modelID))
-          const language = yield* Effect.promise(() => Provider.getLanguage(resolved))
+          const model = input.model ?? (yield* provider.defaultModel())
+          const resolved = yield* provider.getModel(model.providerID, model.modelID)
+          const language = yield* provider.getLanguage(resolved)
 
           const system = [PROMPT_GENERATE]
           yield* Effect.promise(() =>
@@ -393,6 +394,7 @@ export namespace Agent {
   )
 
   export const defaultLayer = layer.pipe(
+    Layer.provide(Provider.defaultLayer),
     Layer.provide(Auth.defaultLayer),
     Layer.provide(Config.defaultLayer),
     Layer.provide(Skill.defaultLayer),
diff --git a/packages/opencode/src/provider/error.ts b/packages/opencode/src/provider/error.ts
index 52e525177a5b..83368f853adf 100644
--- a/packages/opencode/src/provider/error.ts
+++ b/packages/opencode/src/provider/error.ts
@@ -112,7 +112,7 @@ export namespace ProviderError {
     | {
         type: "api_error"
         message: string
-        isRetryable: false
+        isRetryable: boolean
         responseBody: string
       }
 
@@ -121,6 +121,18 @@ export namespace ProviderError {
     if (!body) return
 
     const responseBody = JSON.stringify(body)
+
+    // Anthropic returns {"type":"overloaded_error","message":"Overloaded"} when
+    // at capacity — this is retryable and should not terminate the session.
+    if (body.type === "overloaded_error") {
+      return {
+        type: "api_error",
+        message: typeof body.message === "string" ? body.message : "Provider is overloaded",
+        isRetryable: true,
+        responseBody,
+      }
+    }
+
     if (body.type !== "error") return
 
     switch (body?.error?.code) {
diff --git a/packages/opencode/src/provider/provider.ts b/packages/opencode/src/provider/provider.ts
index c6784f450244..b2f7d848d0f0 100644
--- a/packages/opencode/src/provider/provider.ts
+++ b/packages/opencode/src/provider/provider.ts
@@ -1541,10 +1541,9 @@ export namespace Provider {
     }),
   )
 
-  const { runPromise } = makeRuntime(
-    Service,
-    layer.pipe(Layer.provide(Config.defaultLayer), Layer.provide(Auth.defaultLayer)),
-  )
+  export const defaultLayer = layer.pipe(Layer.provide(Config.defaultLayer), Layer.provide(Auth.defaultLayer))
+
+  const { runPromise } = makeRuntime(Service, defaultLayer)
 
   export async function list() {
     return runPromise((svc) => svc.list())
diff --git a/packages/opencode/src/session/compaction.ts b/packages/opencode/src/session/compaction.ts
index 02a8d9484514..999a37b1226d 100644
--- a/packages/opencode/src/session/compaction.ts
+++ b/packages/opencode/src/session/compaction.ts
@@ -63,7 +63,13 @@ export namespace SessionCompaction {
   export const layer: Layer.Layer<
     Service,
     never,
-    Bus.Service | Config.Service | Session.Service | Agent.Service | Plugin.Service | SessionProcessor.Service
+    | Bus.Service
+    | Config.Service
+    | Session.Service
+    | Agent.Service
+    | Plugin.Service
+    | SessionProcessor.Service
+    | Provider.Service
   > = Layer.effect(
     Service,
     Effect.gen(function* () {
@@ -73,6 +79,7 @@ export namespace SessionCompaction {
       const agents = yield* Agent.Service
       const plugin = yield* Plugin.Service
       const processors = yield* SessionProcessor.Service
+      const provider = yield* Provider.Service
 
       const isOverflow = Effect.fn("SessionCompaction.isOverflow")(function* (input: {
         tokens: MessageV2.Assistant["tokens"]
@@ -170,11 +177,9 @@ export namespace SessionCompaction {
         }
 
         const agent = yield* agents.get("compaction")
-        const model = yield* Effect.promise(() =>
-          agent.model
-            ? Provider.getModel(agent.model.providerID, agent.model.modelID)
-            : Provider.getModel(userMessage.model.providerID, userMessage.model.modelID),
-        )
+        const model = agent.model
+          ? yield* provider.getModel(agent.model.providerID, agent.model.modelID)
+          : yield* provider.getModel(userMessage.model.providerID, userMessage.model.modelID)
         // Allow plugins to inject context or replace compaction prompt.
         const compacting = yield* plugin.trigger(
           "experimental.session.compacting",
@@ -377,6 +382,7 @@ When constructing the summary, try to stick to this template:
   export const defaultLayer = Layer.unwrap(
     Effect.sync(() =>
       layer.pipe(
+        Layer.provide(Provider.defaultLayer),
         Layer.provide(Session.defaultLayer),
         Layer.provide(SessionProcessor.defaultLayer),
         Layer.provide(Agent.defaultLayer),
diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index 083c23cc68f8..78f4fae52111 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -84,6 +84,7 @@ export namespace SessionPrompt {
       const status = yield* SessionStatus.Service
       const sessions = yield* Session.Service
       const agents = yield* Agent.Service
+      const provider = yield* Provider.Service
       const processor = yield* SessionProcessor.Service
       const compaction = yield* SessionCompaction.Service
       const plugin = yield* Plugin.Service
@@ -206,14 +207,14 @@ export namespace SessionPrompt {
 
         const ag = yield* agents.get("title")
         if (!ag) return
+        const mdl = ag.model
+          ? yield* provider.getModel(ag.model.providerID, ag.model.modelID)
+          : ((yield* provider.getSmallModel(input.providerID)) ??
+            (yield* provider.getModel(input.providerID, input.modelID)))
+        const msgs = onlySubtasks
+          ? [{ role: "user" as const, content: subtasks.map((p) => p.prompt).join("\n") }]
+          : yield* Effect.promise(() => MessageV2.toModelMessages(context, mdl))
         const text = yield* Effect.promise(async (signal) => {
-          const mdl = ag.model
-            ? await Provider.getModel(ag.model.providerID, ag.model.modelID)
-            : ((await Provider.getSmallModel(input.providerID)) ??
-              (await Provider.getModel(input.providerID, input.modelID)))
-          const msgs = onlySubtasks
-            ? [{ role: "user" as const, content: subtasks.map((p) => p.prompt).join("\n") }]
-            : await MessageV2.toModelMessages(context, mdl)
           const result = await LLM.stream({
             agent: ag,
             user: firstInfo,
@@ -932,21 +933,35 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         return { info: msg, parts: [part] }
       })
 
-      const getModel = (providerID: ProviderID, modelID: ModelID, sessionID: SessionID) =>
-        Effect.promise(() =>
-          Provider.getModel(providerID, modelID).catch((e) => {
-            if (Provider.ModelNotFoundError.isInstance(e)) {
-              const hint = e.data.suggestions?.length ? ` Did you mean: ${e.data.suggestions.join(", ")}?` : ""
-              Bus.publish(Session.Event.Error, {
-                sessionID,
-                error: new NamedError.Unknown({
-                  message: `Model not found: ${e.data.providerID}/${e.data.modelID}.${hint}`,
-                }).toObject(),
-              })
-            }
-            throw e
-          }),
-        )
+      const getModel = Effect.fn("SessionPrompt.getModel")(function* (
+        providerID: ProviderID,
+        modelID: ModelID,
+        sessionID: SessionID,
+      ) {
+        const exit = yield* provider.getModel(providerID, modelID).pipe(Effect.exit)
+        if (Exit.isSuccess(exit)) return exit.value
+        const err = Cause.squash(exit.cause)
+        if (Provider.ModelNotFoundError.isInstance(err)) {
+          const hint = err.data.suggestions?.length ? ` Did you mean: ${err.data.suggestions.join(", ")}?` : ""
+          yield* bus.publish(Session.Event.Error, {
+            sessionID,
+            error: new NamedError.Unknown({
+              message: `Model not found: ${err.data.providerID}/${err.data.modelID}.${hint}`,
+            }).toObject(),
+          })
+        }
+        return yield* Effect.failCause(exit.cause)
+      })
+
+      const lastModel = Effect.fnUntraced(function* (sessionID: SessionID) {
+        const model = yield* Effect.promise(async () => {
+          for await (const item of MessageV2.stream(sessionID)) {
+            if (item.info.role === "user" && item.info.model) return item.info.model
+          }
+        })
+        if (model) return model
+        return yield* provider.defaultModel()
+      })
 
       const createUserMessage = Effect.fn("SessionPrompt.createUserMessage")(function* (input: PromptInput) {
         const agentName = input.agent || (yield* agents.defaultAgent())
@@ -960,9 +975,12 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         }
 
         const model = input.model ?? ag.model ?? (yield* lastModel(input.sessionID))
+        const same = ag.model && model.providerID === ag.model.providerID && model.modelID === ag.model.modelID
         const full =
-          !input.variant && ag.variant
-            ? yield* Effect.promise(() => Provider.getModel(model.providerID, model.modelID).catch(() => undefined))
+          !input.variant && ag.variant && same
+            ? yield* provider
+                .getModel(model.providerID, model.modelID)
+                .pipe(Effect.catch(() => Effect.succeed(undefined)))
             : undefined
         const variant = input.variant ?? (ag.variant && full?.variants?.[ag.variant] ? ag.variant : undefined)
 
@@ -1109,7 +1127,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
                   ]
                   const read = yield* Effect.promise(() => ReadTool.init()).pipe(
                     Effect.flatMap((t) =>
-                      Effect.promise(() => Provider.getModel(info.model.providerID, info.model.modelID)).pipe(
+                      provider.getModel(info.model.providerID, info.model.modelID).pipe(
                         Effect.flatMap((mdl) =>
                           Effect.promise(() =>
                             t.execute(args, {
@@ -1711,6 +1729,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         Layer.provide(FileTime.defaultLayer),
         Layer.provide(ToolRegistry.defaultLayer),
         Layer.provide(Truncate.layer),
+        Layer.provide(Provider.defaultLayer),
         Layer.provide(AppFileSystem.defaultLayer),
         Layer.provide(Plugin.defaultLayer),
         Layer.provide(Session.defaultLayer),
@@ -1856,15 +1875,6 @@ NOTE: At any point in time through this workflow you should feel free to ask the
     return runPromise((svc) => svc.command(CommandInput.parse(input)))
   }
 
-  const lastModel = Effect.fnUntraced(function* (sessionID: SessionID) {
-    return yield* Effect.promise(async () => {
-      for await (const item of MessageV2.stream(sessionID)) {
-        if (item.info.role === "user" && item.info.model) return item.info.model
-      }
-      return Provider.defaultModel()
-    })
-  })
-
   /** @internal Exported for testing */
   export function createStructuredOutputTool(input: {
     schema: Record<string, any>
diff --git a/packages/opencode/src/session/retry.ts b/packages/opencode/src/session/retry.ts
index 8ba48375bcfe..86325802f895 100644
--- a/packages/opencode/src/session/retry.ts
+++ b/packages/opencode/src/session/retry.ts
@@ -73,6 +73,9 @@ export namespace SessionRetry {
     if (!json || typeof json !== "object") return undefined
     const code = typeof json.code === "string" ? json.code : ""
 
+    if (json.type === "overloaded_error") {
+      return "Provider is overloaded"
+    }
     if (json.type === "error" && json.error?.type === "too_many_requests") {
       return "Too Many Requests"
     }
diff --git a/packages/opencode/test/fake/provider.ts b/packages/opencode/test/fake/provider.ts
new file mode 100644
index 000000000000..b6f72f53dbed
--- /dev/null
+++ b/packages/opencode/test/fake/provider.ts
@@ -0,0 +1,81 @@
+import { Effect, Layer } from "effect"
+import { Provider } from "../../src/provider/provider"
+import { ModelID, ProviderID } from "../../src/provider/schema"
+
+export namespace ProviderTest {
+  export function model(override: Partial<Provider.Model> = {}): Provider.Model {
+    const id = override.id ?? ModelID.make("gpt-5.2")
+    const providerID = override.providerID ?? ProviderID.make("openai")
+    return {
+      id,
+      providerID,
+      name: "Test Model",
+      capabilities: {
+        toolcall: true,
+        attachment: false,
+        reasoning: false,
+        temperature: true,
+        interleaved: false,
+        input: { text: true, image: false, audio: false, video: false, pdf: false },
+        output: { text: true, image: false, audio: false, video: false, pdf: false },
+      },
+      api: { id, url: "https://example.com", npm: "@ai-sdk/openai" },
+      cost: { input: 0, output: 0, cache: { read: 0, write: 0 } },
+      limit: { context: 200_000, output: 10_000 },
+      status: "active",
+      options: {},
+      headers: {},
+      release_date: "2025-01-01",
+      ...override,
+    }
+  }
+
+  export function info(override: Partial<Provider.Info> = {}, mdl = model()): Provider.Info {
+    const id = override.id ?? mdl.providerID
+    return {
+      id,
+      name: "Test Provider",
+      source: "config",
+      env: [],
+      options: {},
+      models: { [mdl.id]: mdl },
+      ...override,
+    }
+  }
+
+  export function fake(override: Partial<Provider.Interface> & { model?: Provider.Model; info?: Provider.Info } = {}) {
+    const mdl = override.model ?? model()
+    const row = override.info ?? info({}, mdl)
+    return {
+      model: mdl,
+      info: row,
+      layer: Layer.succeed(
+        Provider.Service,
+        Provider.Service.of({
+          list: Effect.fn("TestProvider.list")(() => Effect.succeed({ [row.id]: row })),
+          getProvider: Effect.fn("TestProvider.getProvider")((providerID) => {
+            if (providerID === row.id) return Effect.succeed(row)
+            return Effect.die(new Error(`Unknown test provider: ${providerID}`))
+          }),
+          getModel: Effect.fn("TestProvider.getModel")((providerID, modelID) => {
+            if (providerID === row.id && modelID === mdl.id) return Effect.succeed(mdl)
+            return Effect.die(new Error(`Unknown test model: ${providerID}/${modelID}`))
+          }),
+          getLanguage: Effect.fn("TestProvider.getLanguage")(() =>
+            Effect.die(new Error("ProviderTest.getLanguage not configured")),
+          ),
+          closest: Effect.fn("TestProvider.closest")((providerID) =>
+            Effect.succeed(providerID === row.id ? { providerID: row.id, modelID: mdl.id } : undefined),
+          ),
+          getSmallModel: Effect.fn("TestProvider.getSmallModel")((providerID) =>
+            Effect.succeed(providerID === row.id ? mdl : undefined),
+          ),
+          defaultModel: Effect.fn("TestProvider.defaultModel")(() =>
+            Effect.succeed({ providerID: row.id, modelID: mdl.id }),
+          ),
+          ...override,
+        }),
+      ),
+    }
+  }
+}
diff --git a/packages/opencode/test/session/compaction.test.ts b/packages/opencode/test/session/compaction.test.ts
index e6d715728d34..f1d61babfaf5 100644
--- a/packages/opencode/test/session/compaction.test.ts
+++ b/packages/opencode/test/session/compaction.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, mock, spyOn, test } from "bun:test"
+import { afterEach, describe, expect, mock, test } from "bun:test"
 import { APICallError } from "ai"
 import { Cause, Effect, Exit, Layer, ManagedRuntime } from "effect"
 import * as Stream from "effect/Stream"
@@ -20,9 +20,9 @@ import { MessageID, PartID, SessionID } from "../../src/session/schema"
 import { SessionStatus } from "../../src/session/status"
 import { ModelID, ProviderID } from "../../src/provider/schema"
 import type { Provider } from "../../src/provider/provider"
-import * as ProviderModule from "../../src/provider/provider"
 import * as SessionProcessorModule from "../../src/session/processor"
 import { Snapshot } from "../../src/snapshot"
+import { ProviderTest } from "../fake/provider"
 
 Log.init({ print: false })
 
@@ -65,6 +65,8 @@ function createModel(opts: {
   } as Provider.Model
 }
 
+const wide = () => ProviderTest.fake({ model: createModel({ context: 100_000, output: 32_000 }) })
+
 async function user(sessionID: SessionID, text: string) {
   const msg = await Session.updateMessage({
     id: MessageID.ascending(),
@@ -162,10 +164,11 @@ function layer(result: "continue" | "compact") {
   )
 }
 
-function runtime(result: "continue" | "compact", plugin = Plugin.defaultLayer) {
+function runtime(result: "continue" | "compact", plugin = Plugin.defaultLayer, provider = ProviderTest.fake()) {
   const bus = Bus.layer
   return ManagedRuntime.make(
     Layer.mergeAll(SessionCompaction.layer, bus).pipe(
+      Layer.provide(provider.layer),
       Layer.provide(Session.defaultLayer),
       Layer.provide(layer(result)),
       Layer.provide(Agent.defaultLayer),
@@ -198,12 +201,13 @@ function llm() {
   }
 }
 
-function liveRuntime(layer: Layer.Layer<LLM.Service>) {
+function liveRuntime(layer: Layer.Layer<LLM.Service>, provider = ProviderTest.fake()) {
   const bus = Bus.layer
   const status = SessionStatus.layer.pipe(Layer.provide(bus))
   const processor = SessionProcessorModule.SessionProcessor.layer
   return ManagedRuntime.make(
     Layer.mergeAll(SessionCompaction.layer.pipe(Layer.provide(processor)), processor, bus, status).pipe(
+      Layer.provide(provider.layer),
       Layer.provide(Session.defaultLayer),
       Layer.provide(Snapshot.defaultLayer),
       Layer.provide(layer),
@@ -544,14 +548,12 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         const msg = await user(session.id, "hello")
         const msgs = await Session.messages({ sessionID: session.id })
         const done = defer()
         let seen = false
-        const rt = runtime("continue")
+        const rt = runtime("continue", Plugin.defaultLayer, wide())
         let unsub: (() => void) | undefined
         try {
           unsub = await rt.runPromise(
@@ -596,11 +598,9 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         const msg = await user(session.id, "hello")
-        const rt = runtime("compact")
+        const rt = runtime("compact", Plugin.defaultLayer, wide())
         try {
           const msgs = await Session.messages({ sessionID: session.id })
           const result = await rt.runPromise(
@@ -636,11 +636,9 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         const msg = await user(session.id, "hello")
-        const rt = runtime("continue")
+        const rt = runtime("continue", Plugin.defaultLayer, wide())
         try {
           const msgs = await Session.messages({ sessionID: session.id })
           const result = await rt.runPromise(
@@ -678,8 +676,6 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         await user(session.id, "root")
         const replay = await user(session.id, "image")
@@ -693,7 +689,7 @@ describe("session.compaction.process", () => {
           url: "https://example.com/cat.png",
         })
         const msg = await user(session.id, "current")
-        const rt = runtime("continue")
+        const rt = runtime("continue", Plugin.defaultLayer, wide())
         try {
           const msgs = await Session.messages({ sessionID: session.id })
           const result = await rt.runPromise(
@@ -728,13 +724,11 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         await user(session.id, "earlier")
         const msg = await user(session.id, "current")
 
-        const rt = runtime("continue")
+        const rt = runtime("continue", Plugin.defaultLayer, wide())
         try {
           const msgs = await Session.messages({ sessionID: session.id })
           const result = await rt.runPromise(
@@ -790,13 +784,11 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         const msg = await user(session.id, "hello")
         const msgs = await Session.messages({ sessionID: session.id })
         const abort = new AbortController()
-        const rt = liveRuntime(stub.layer)
+        const rt = liveRuntime(stub.layer, wide())
         let off: (() => void) | undefined
         let run: Promise<"continue" | "stop"> | undefined
         try {
@@ -866,13 +858,11 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         const msg = await user(session.id, "hello")
         const msgs = await Session.messages({ sessionID: session.id })
         const abort = new AbortController()
-        const rt = runtime("continue", plugin(ready))
+        const rt = runtime("continue", plugin(ready), wide())
         let run: Promise<"continue" | "stop"> | undefined
         try {
           run = rt
@@ -970,11 +960,9 @@ describe("session.compaction.process", () => {
     await Instance.provide({
       directory: tmp.path,
       fn: async () => {
-        spyOn(ProviderModule.Provider, "getModel").mockResolvedValue(createModel({ context: 100_000, output: 32_000 }))
-
         const session = await Session.create({})
         const msg = await user(session.id, "hello")
-        const rt = liveRuntime(stub.layer)
+        const rt = liveRuntime(stub.layer, wide())
         try {
           const msgs = await Session.messages({ sessionID: session.id })
           await rt.runPromise(
diff --git a/packages/opencode/test/session/prompt-concurrency.test.ts b/packages/opencode/test/session/prompt-concurrency.test.ts
deleted file mode 100644
index 19e1c4bf59cf..000000000000
--- a/packages/opencode/test/session/prompt-concurrency.test.ts
+++ /dev/null
@@ -1,247 +0,0 @@
-import { describe, expect, spyOn, test } from "bun:test"
-import { Instance } from "../../src/project/instance"
-import { Provider } from "../../src/provider/provider"
-import { Session } from "../../src/session"
-import { MessageV2 } from "../../src/session/message-v2"
-import { SessionPrompt } from "../../src/session/prompt"
-import { SessionStatus } from "../../src/session/status"
-import { MessageID, PartID, SessionID } from "../../src/session/schema"
-import { Log } from "../../src/util/log"
-import { tmpdir } from "../fixture/fixture"
-
-Log.init({ print: false })
-
-function deferred() {
-  let resolve!: () => void
-  const promise = new Promise<void>((done) => {
-    resolve = done
-  })
-  return { promise, resolve }
-}
-
-// Helper: seed a session with a user message + finished assistant message
-// so loop() exits immediately without calling any LLM
-async function seed(sessionID: SessionID) {
-  const userMsg: MessageV2.Info = {
-    id: MessageID.ascending(),
-    role: "user",
-    sessionID,
-    time: { created: Date.now() },
-    agent: "build",
-    model: { providerID: "openai" as any, modelID: "gpt-5.2" as any },
-  }
-  await Session.updateMessage(userMsg)
-  await Session.updatePart({
-    id: PartID.ascending(),
-    messageID: userMsg.id,
-    sessionID,
-    type: "text",
-    text: "hello",
-  })
-
-  const assistantMsg: MessageV2.Info = {
-    id: MessageID.ascending(),
-    role: "assistant",
-    parentID: userMsg.id,
-    sessionID,
-    mode: "build",
-    agent: "build",
-    cost: 0,
-    path: { cwd: "/tmp", root: "/tmp" },
-    tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
-    modelID: "gpt-5.2" as any,
-    providerID: "openai" as any,
-    time: { created: Date.now(), completed: Date.now() },
-    finish: "stop",
-  }
-  await Session.updateMessage(assistantMsg)
-  await Session.updatePart({
-    id: PartID.ascending(),
-    messageID: assistantMsg.id,
-    sessionID,
-    type: "text",
-    text: "hi there",
-  })
-
-  return { userMsg, assistantMsg }
-}
-
-describe("session.prompt concurrency", () => {
-  test("loop returns assistant message and sets status to idle", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await Instance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const session = await Session.create({})
-        await seed(session.id)
-
-        const result = await SessionPrompt.loop({ sessionID: session.id })
-        expect(result.info.role).toBe("assistant")
-        if (result.info.role === "assistant") expect(result.info.finish).toBe("stop")
-
-        const status = await SessionStatus.get(session.id)
-        expect(status.type).toBe("idle")
-      },
-    })
-  })
-
-  test("concurrent loop callers get the same result", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await Instance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const session = await Session.create({})
-        await seed(session.id)
-
-        const [a, b] = await Promise.all([
-          SessionPrompt.loop({ sessionID: session.id }),
-          SessionPrompt.loop({ sessionID: session.id }),
-        ])
-
-        expect(a.info.id).toBe(b.info.id)
-        expect(a.info.role).toBe("assistant")
-      },
-    })
-  })
-
-  test("assertNotBusy throws when loop is running", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await Instance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const session = await Session.create({})
-        const userMsg: MessageV2.Info = {
-          id: MessageID.ascending(),
-          role: "user",
-          sessionID: session.id,
-          time: { created: Date.now() },
-          agent: "build",
-          model: { providerID: "openai" as any, modelID: "gpt-5.2" as any },
-        }
-        await Session.updateMessage(userMsg)
-        await Session.updatePart({
-          id: PartID.ascending(),
-          messageID: userMsg.id,
-          sessionID: session.id,
-          type: "text",
-          text: "hello",
-        })
-
-        const ready = deferred()
-        const gate = deferred()
-        const getModel = spyOn(Provider, "getModel").mockImplementation(async () => {
-          ready.resolve()
-          await gate.promise
-          throw new Error("test stop")
-        })
-
-        try {
-          const loopPromise = SessionPrompt.loop({ sessionID: session.id }).catch(() => undefined)
-          await ready.promise
-
-          await expect(SessionPrompt.assertNotBusy(session.id)).rejects.toBeInstanceOf(Session.BusyError)
-
-          gate.resolve()
-          await loopPromise
-        } finally {
-          gate.resolve()
-          getModel.mockRestore()
-        }
-
-        // After loop completes, assertNotBusy should succeed
-        await SessionPrompt.assertNotBusy(session.id)
-      },
-    })
-  })
-
-  test("cancel sets status to idle", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await Instance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const session = await Session.create({})
-        // Seed only a user message — loop must call getModel to proceed
-        const userMsg: MessageV2.Info = {
-          id: MessageID.ascending(),
-          role: "user",
-          sessionID: session.id,
-          time: { created: Date.now() },
-          agent: "build",
-          model: { providerID: "openai" as any, modelID: "gpt-5.2" as any },
-        }
-        await Session.updateMessage(userMsg)
-        await Session.updatePart({
-          id: PartID.ascending(),
-          messageID: userMsg.id,
-          sessionID: session.id,
-          type: "text",
-          text: "hello",
-        })
-        // Also seed an assistant message so lastAssistant() fallback can find it
-        const assistantMsg: MessageV2.Info = {
-          id: MessageID.ascending(),
-          role: "assistant",
-          parentID: userMsg.id,
-          sessionID: session.id,
-          mode: "build",
-          agent: "build",
-          cost: 0,
-          path: { cwd: "/tmp", root: "/tmp" },
-          tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
-          modelID: "gpt-5.2" as any,
-          providerID: "openai" as any,
-          time: { created: Date.now() },
-        }
-        await Session.updateMessage(assistantMsg)
-        await Session.updatePart({
-          id: PartID.ascending(),
-          messageID: assistantMsg.id,
-          sessionID: session.id,
-          type: "text",
-          text: "hi there",
-        })
-
-        const ready = deferred()
-        const gate = deferred()
-        const getModel = spyOn(Provider, "getModel").mockImplementation(async () => {
-          ready.resolve()
-          await gate.promise
-          throw new Error("test stop")
-        })
-
-        try {
-          // Start loop — it will block in getModel (assistant has no finish, so loop continues)
-          const loopPromise = SessionPrompt.loop({ sessionID: session.id })
-
-          await ready.promise
-
-          await SessionPrompt.cancel(session.id)
-
-          const status = await SessionStatus.get(session.id)
-          expect(status.type).toBe("idle")
-
-          // loop should resolve cleanly, not throw "All fibers interrupted"
-          const result = await loopPromise
-          expect(result.info.role).toBe("assistant")
-          expect(result.info.id).toBe(assistantMsg.id)
-        } finally {
-          gate.resolve()
-          getModel.mockRestore()
-        }
-      },
-    })
-  }, 10000)
-
-  test("cancel on idle session just sets idle", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await Instance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const session = await Session.create({})
-        await SessionPrompt.cancel(session.id)
-        const status = await SessionStatus.get(session.id)
-        expect(status.type).toBe("idle")
-      },
-    })
-  })
-})
diff --git a/packages/opencode/test/session/prompt-effect.test.ts b/packages/opencode/test/session/prompt-effect.test.ts
index 98111bb3a269..28b4cf15cba8 100644
--- a/packages/opencode/test/session/prompt-effect.test.ts
+++ b/packages/opencode/test/session/prompt-effect.test.ts
@@ -12,6 +12,7 @@ import { LSP } from "../../src/lsp"
 import { MCP } from "../../src/mcp"
 import { Permission } from "../../src/permission"
 import { Plugin } from "../../src/plugin"
+import { Provider as ProviderSvc } from "../../src/provider/provider"
 import type { Provider } from "../../src/provider/provider"
 import { ModelID, ProviderID } from "../../src/provider/schema"
 import { Session } from "../../src/session"
@@ -151,6 +152,7 @@ function makeHttp() {
     Permission.layer,
     Plugin.defaultLayer,
     Config.defaultLayer,
+    ProviderSvc.defaultLayer,
     filetime,
     lsp,
     mcp,