refactor(sse): restore three executor types the runtime already relied on (#8520)

Three independent root causes in the TS 7 executor slice (#8484), each a
declaration that had drifted behind the code using it. All type-only —
no behavior change, verified by running the new tests against the parent
commit's sources (7/7 pass there too).

mimocode — AccountState was missing `proxy`, but syncAccountsFromCredentials()
writes it on every account and getProxyDispatcher() reads it. The #3837/#5521
contract ("always present, null when unconfigured") lived only in a comment.
Declared as AccountProxyConfig["proxy"] so the two stay in lockstep. (4)

opencode — the tools-truncation block narrowed `modifiedBody` with
`typeof === "object"` but, unlike the client_metadata block directly above it,
omitted `!Array.isArray()` and the Record cast, so `.tools` was unreachable on
`object`. Adopted the neighbouring block's idiom. Behavior is identical: the
old code reached `.tools` on arrays too and relied on Array.isArray(undefined)
short-circuiting. (4)

zed-hosted — enqueueSseObject/finish/processLine were annotated
ReadableStreamDefaultController but are driven from a TransformStream, whose
controller has no close(). All three only ever enqueue, so they are now typed
by that single capability (SseEnqueueTarget). (3)

310 -> 299 diagnostics, zero new, on a line-number-agnostic diff of the full
tsc error set.

Tests: new tests/unit/ts7-executor-shared-shapes.test.ts pins the tools
truncation (previously uncovered) and the proxy-always-present contract. The
zed-hosted transform is already covered end-to-end by
zed-hosted-think-close-marker.test.ts. 300/300 across the 26 affected files.

Co-authored-by: backryun <busan011@ormbiz.co.kr>

open-sse/executors/mimocode.ts

@@ -100,6 +100,12 @@ interface AccountState {
   expiresAt: number;
   cooldownUntil: number;
   consecutiveFails: number;
+  /**
+   * #3837/#5521: the account's resolved proxy, or `null` when none is configured.
+   * Always present (never `undefined`) so callers can read `acct.proxy` directly —
+   * syncAccountsFromCredentials() writes it on every account on every sync.
+   */
+  proxy: AccountProxyConfig["proxy"];
 }
 
 function parseJwtExp(jwt: string): number {

open-sse/executors/opencode.ts

@@ -338,13 +338,11 @@ export class OpencodeExecutor extends BaseExecutor {
     ) {
       delete (modifiedBody as Record<string, unknown>).client_metadata;
     }
-    if (
-      modifiedBody &&
-      typeof modifiedBody === "object" &&
-      Array.isArray(modifiedBody.tools) &&
-      modifiedBody.tools.length > 128
-    ) {
-      modifiedBody.tools = modifiedBody.tools.slice(0, 128);
+    if (modifiedBody && typeof modifiedBody === "object" && !Array.isArray(modifiedBody)) {
+      const mb = modifiedBody as Record<string, unknown>;
+      if (Array.isArray(mb.tools) && mb.tools.length > 128) {
+        mb.tools = mb.tools.slice(0, 128);
+      }
     }
     if (modifiedBody && typeof modifiedBody === "object" && !Array.isArray(modifiedBody)) {
       const mb = modifiedBody as Record<string, unknown>;

open-sse/executors/zed-hosted.ts

@@ -117,8 +117,18 @@ function createErrorChunk(model: string, message: string): Record<string, unknow
   };
 }
 
+/**
+ * The single controller capability these SSE helpers use. They only ever enqueue —
+ * never `close()`, never read `desiredSize` — so typing them by that one method lets
+ * the same code serve both stream kinds. The wider
+ * `ReadableStreamDefaultController` annotation rejected every call site, because the
+ * helpers are driven from a TransformStream and `TransformStreamDefaultController`
+ * has no `close()`.
+ */
+type SseEnqueueTarget = Pick<ReadableStreamDefaultController<Uint8Array>, "enqueue">;
+
 function enqueueSseObject(
-  controller: ReadableStreamDefaultController<Uint8Array>,
+  controller: SseEnqueueTarget,
   encoder: TextEncoder,
   chunk: unknown
 ): void {
@@ -202,7 +212,7 @@ function wrapZedCompletionStream(
   let buffer = "";
   let done = false;
 
-  const finish = (controller: ReadableStreamDefaultController<Uint8Array>) => {
+  const finish = (controller: SseEnqueueTarget) => {
     if (done) return;
     const finalChunk = convertProviderEvent(provider, null, state);
     enqueueSseObject(controller, encoder, finalChunk);
@@ -210,7 +220,7 @@ function wrapZedCompletionStream(
     done = true;
   };
 
-  const processLine = (line: string, controller: ReadableStreamDefaultController<Uint8Array>) => {
+  const processLine = (line: string, controller: SseEnqueueTarget) => {
     if (done) return;
     const payload = unwrapZedLine(line);
     if (!payload) return;

tests/unit/ts7-executor-shared-shapes.test.ts

@@ -0,0 +1,145 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+const { OpencodeExecutor } = await import("../../open-sse/executors/opencode.ts");
+const { MimocodeExecutor } = await import("../../open-sse/executors/mimocode.ts");
+
+/**
+ * Behavioral guards for the three type-only fixes in the TS 7 executor slice
+ * (see #8484). Each fix restored a type the code already depended on at runtime;
+ * these tests pin the runtime contracts so a future "simplification" of the
+ * annotations cannot silently change behavior.
+ *
+ * The zed-hosted `SseEnqueueTarget` fix is already covered end-to-end by
+ * `zed-hosted-think-close-marker.test.ts`, which drives the same TransformStream
+ * that failed to type-check — no duplicate added here.
+ */
+
+describe("OpencodeExecutor — tools truncation survives the narrowing fix", () => {
+  const executor = new OpencodeExecutor("opencode-go");
+  const CREDENTIALS = { apiKey: "k" } as Record<string, unknown>;
+
+  const tools = (n: number) =>
+    Array.from({ length: n }, (_, i) => ({
+      type: "function",
+      function: { name: `tool_${i}`, parameters: {} },
+    }));
+
+  function bodyWith(toolCount: number) {
+    return {
+      model: "oc/kimi-k2.6",
+      stream: true,
+      messages: [{ role: "user", content: "hi" }],
+      tools: tools(toolCount),
+    };
+  }
+
+  it("truncates an over-long tools array to 128 entries", () => {
+    const out = executor.transformRequest("oc/kimi-k2.6", bodyWith(200), true, CREDENTIALS) as {
+      tools: unknown[];
+    };
+    assert.equal(out.tools.length, 128, "upstream rejects more than 128 tools");
+    assert.deepEqual(
+      (out.tools[127] as { function: { name: string } }).function.name,
+      "tool_127",
+      "truncation keeps the first 128 in order, not an arbitrary slice"
+    );
+  });
+
+  it("leaves a within-limit tools array untouched", () => {
+    const out = executor.transformRequest("oc/kimi-k2.6", bodyWith(10), true, CREDENTIALS) as {
+      tools: unknown[];
+    };
+    assert.equal(out.tools.length, 10);
+  });
+
+  it("is a no-op when the body carries no tools", () => {
+    const body = {
+      model: "oc/kimi-k2.6",
+      stream: true,
+      messages: [{ role: "user", content: "hi" }],
+    };
+    const out = executor.transformRequest("oc/kimi-k2.6", body, true, CREDENTIALS) as Record<
+      string,
+      unknown
+    >;
+    assert.equal("tools" in out, false);
+    assert.ok(Array.isArray(out.messages), "messages preserved");
+  });
+
+  it("leaves an array-shaped body alone (pins the !Array.isArray guard)", () => {
+    // The pre-fix condition reached `.tools` on any object, arrays included, and
+    // relied on `Array.isArray(undefined)` short-circuiting. The explicit
+    // !Array.isArray() guard must keep that outcome identical.
+    const arrayBody = [{ role: "user", content: "hi" }] as unknown as Record<string, unknown>;
+    const out = executor.transformRequest("oc/kimi-k2.6", arrayBody, true, CREDENTIALS);
+    assert.ok(Array.isArray(out), "array body must pass through as an array");
+    assert.equal((out as unknown[]).length, 1);
+  });
+});
+
+describe("MimocodeExecutor — AccountState.proxy is always present (#3837/#5521)", () => {
+  const FP = "fingerprint-1";
+
+  function accountsOf(exec: unknown): Array<Record<string, unknown>> {
+    return (exec as { accounts: Array<Record<string, unknown>> }).accounts;
+  }
+
+  function sync(exec: unknown, credentials: unknown): void {
+    (exec as { syncAccountsFromCredentials(c: unknown): void }).syncAccountsFromCredentials(
+      credentials
+    );
+  }
+
+  it("defaults proxy to null — not undefined — when no accountProxies are configured", () => {
+    const exec = new MimocodeExecutor();
+    accountsOf(exec).length = 0;
+    accountsOf(exec).push({
+      fingerprint: FP,
+      jwt: "",
+      expiresAt: 0,
+      cooldownUntil: 0,
+      consecutiveFails: 0,
+    });
+
+    sync(exec, { providerSpecificData: {} });
+
+    const account = accountsOf(exec)[0];
+    assert.ok("proxy" in account, "every account must expose a proxy key");
+    assert.equal(account.proxy, null, "unconfigured proxy is null, never undefined");
+  });
+
+  it("resolves a configured proxy onto the matching account", () => {
+    const exec = new MimocodeExecutor();
+    accountsOf(exec).length = 0;
+    accountsOf(exec).push({
+      fingerprint: FP,
+      jwt: "",
+      expiresAt: 0,
+      cooldownUntil: 0,
+      consecutiveFails: 0,
+    });
+
+    const proxy = { type: "http", host: "p1.example.com", port: 1080 };
+    sync(exec, { providerSpecificData: { accountProxies: [{ fingerprint: FP, proxy }] } });
+
+    assert.deepEqual(accountsOf(exec)[0].proxy, proxy);
+  });
+
+  it("clears a previously-resolved proxy back to null when config drops it", () => {
+    const exec = new MimocodeExecutor();
+    accountsOf(exec).length = 0;
+    accountsOf(exec).push({
+      fingerprint: FP,
+      jwt: "",
+      expiresAt: 0,
+      cooldownUntil: 0,
+      consecutiveFails: 0,
+      proxy: { type: "http", host: "stale.example.com", port: 8080 },
+    });
+
+    sync(exec, { providerSpecificData: { accountProxies: [] } });
+
+    assert.equal(accountsOf(exec)[0].proxy, null, "a removed proxy must not linger on the account");
+  });
+});