fix(retry): use plain Cause.done + Pull.isDoneCause

Both reviewers (spec + quality, codex-5.3) flagged that retry.ts:129/131
used Effect.failCause(Cause.Done(...) as unknown as Cause.Cause<number>)
with double casts to terminate the schedule. Plan A.2.2 specifies
'return Cause.done(meta.attempt)' directly; the cast pattern was hiding
a type mismatch and making the control flow harder to reason about.

- retry.ts: replace both Effect.failCause casts with plain
  Cause.done(meta.attempt) — the Effect<never, Done<number>> that
  fromStepWithMetadata already expects as a stop signal.
- retry.test.ts: my original A.2.1 assertion used Cause.isDone(cause),
  which takes a Done value and returned false on a Cause<Done>. Switch
  to Pull.isDoneCause(cause), which correctly recognizes a Cause whose
  reason is a Done marker. Drop unused Cause import.

All 54 targeted tests pass, typecheck clean. Addresses spec+quality
review of 2176730.

Author: tesdal

packages/opencode/src/session/retry.ts

@@ -126,9 +126,9 @@ export function policy(opts: {
       const error = opts.parse(meta.input)
       const message = retryable(error)
       const transport = transportMessage(error)
-      if (!message) return Effect.failCause(Cause.Done(meta.attempt) as unknown as Cause.Cause<number>)
+      if (!message) return Cause.done(meta.attempt)
       if (transport && !MessageV2.APIError.isInstance(error) && meta.attempt > TRANSPORT_RETRY_CAP) {
-        return Effect.failCause(Cause.Done(meta.attempt) as unknown as Cause.Cause<number>)
+        return Cause.done(meta.attempt)
       }
       return Effect.gen(function* () {
         const wait = delay(meta.attempt, MessageV2.APIError.isInstance(error) ? error : undefined)

packages/opencode/test/session/retry.test.ts

@@ -2,7 +2,7 @@ import { describe, expect, test } from "bun:test"
 import type { NamedError } from "@opencode-ai/shared/util/error"
 import { APICallError } from "ai"
 import { setTimeout as sleep } from "node:timers/promises"
-import { Cause, Effect, Exit, Layer, Schedule } from "effect"
+import { Effect, Exit, Layer, Pull, Schedule } from "effect"
 import { SessionRetry } from "../../src/session/retry"
 import { MessageV2 } from "../../src/session/message-v2"
 import { SSEStallError } from "../../src/provider/provider"
@@ -307,9 +307,10 @@ describe("SessionRetry.policy — transport retry budget", () => {
         expect(setCalls).toBe(5)
         expect(terminal).toBeDefined()
         if (!Exit.isFailure(terminal!)) throw new Error("expected terminal exit to be Failure")
-        // Policy signals "stop retrying" via Cause.done(n), not Cause.fail.
-        // Cause.isDone confirms schedule completed normally, not crashed.
-        expect(Cause.isDone(terminal.cause)).toBe(true)
+        // Policy signals "stop retrying" via Cause.done(n), surfaced by Pull
+        // as a Failure whose cause contains a Done reason. Pull.isDoneCause
+        // confirms schedule completed normally (not crashed via fail/die).
+        expect(Pull.isDoneCause(terminal.cause)).toBe(true)
       }),
   )
 })