Narrow provider status errors with Predicate

ts/EFFECT_NATIVE_REWRITE_AUDIT.md

@@ -13,7 +13,7 @@ Verified source roots:
 - Installed Effect beta used by this workspace: `ts/node_modules/effect`
 
 Current signal counts from `ts/packages` after the 2026-06-02 Text completion
-generator boundary slice:
+provider status narrowing slice:
 
 | Signal | Count |
 | --- | ---: |
@@ -76,6 +76,8 @@ Notes:
   `Effect.runPromise(Effect.fail(...))` fallback and the related
   `AsyncGenerator`/`IteratorResult` assertions from
   `model/text-completion/common.ts`.
+- The text completion provider status slice replaced manual status/statusCode
+  record assertions with `effect/Predicate` narrowing.
 - `Record<string, any>` and `throwLibrarianServiceError` are now clean in
   `ts/packages`.
 
@@ -589,6 +591,24 @@ Notes:
   - `cd ts && bun run test`
   - `git diff --check`
 
+### 2026-06-02: Text Completion Provider Status Narrowing Slice
+
+- Status: migrated and root-verified.
+- Completed:
+  - `ts/packages/flow/src/model/text-completion/common.ts` now uses
+    `effect/Predicate` narrowing for provider `status` / `statusCode`
+    inspection instead of local record assertions.
+  - `ts/packages/flow/src/__tests__/text-completion-common.test.ts` covers
+    both rate-limit status fields.
+- Verification:
+  - `bun run --cwd ts/packages/flow test -- src/__tests__/text-completion-common.test.ts`
+  - `bun run --cwd ts/packages/flow build`
+  - `cd ts && bun run check`
+  - `bun run --cwd ts/packages/flow test`
+  - `cd ts && bun run build`
+  - `cd ts && bun run test`
+  - `git diff --check`
+
 ## Subagent Findings To Preserve
 
 - MCP/workbench:

ts/packages/flow/src/__tests__/text-completion-common.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "@effect/vitest";
 import type { LlmChunk } from "@trustgraph/base";
-import { providerRuntimeError, toAsyncGenerator } from "../model/text-completion/common.js";
+import { providerRuntimeError, providerStatusError, toAsyncGenerator } from "../model/text-completion/common.js";
 
 const emptyChunkIterator = (): AsyncIterable<LlmChunk> => ({
   [Symbol.asyncIterator]: () => ({
@@ -9,6 +9,18 @@ const emptyChunkIterator = (): AsyncIterable<LlmChunk> => ({
 });
 
 describe("text completion common helpers", () => {
+  it("maps provider rate-limit status fields to tagged retry errors", () => {
+    expect(providerStatusError("test-provider", { status: 429 })).toMatchObject({
+      _tag: "TooManyRequestsError",
+      message: "Rate limit exceeded",
+    });
+
+    expect(providerStatusError("test-provider", { statusCode: 429 })).toMatchObject({
+      _tag: "TooManyRequestsError",
+      message: "Rate limit exceeded",
+    });
+  });
+
   it("maps fallback generator throw failures into tagged provider errors", async () => {
     const generator = toAsyncGenerator(
       emptyChunkIterator(),

ts/packages/flow/src/model/text-completion/common.ts

@@ -5,6 +5,7 @@ import {
 } from "@trustgraph/base";
 import { Config, Effect } from "effect";
 import * as O from "effect/Option";
+import * as Predicate from "effect/Predicate";
 import * as S from "effect/Schema";
 
 export class TextCompletionConfigError extends S.TaggedErrorClass<TextCompletionConfigError>()(
@@ -68,11 +69,11 @@ export const providerStatusError = (
   provider: string,
   error: unknown,
 ): TextCompletionRuntimeError => {
-  const status = typeof error === "object" && error !== null && "status" in error
-    ? (error as { readonly status?: unknown }).status
+  const status = Predicate.isObject(error) && Predicate.hasProperty(error, "status")
+    ? error.status
     : undefined;
-  const statusCode = typeof error === "object" && error !== null && "statusCode" in error
-    ? (error as { readonly statusCode?: unknown }).statusCode
+  const statusCode = Predicate.isObject(error) && Predicate.hasProperty(error, "statusCode")
+    ? error.statusCode
     : undefined;
   return status === 429 || statusCode === 429
     ? TooManyRequestsError.make({ message: "Rate limit exceeded" })