@@ -13,32 +13,31 @@ Callers import from `@corbits/embedding`. The barrel is the public surface:
 | `embedTexts` | Batch texts, post sequentially, return `number[][]` in input order |
 | `probeEmbedDims` | Embed one probe string; report the vector length that came back |
 | `EmbedConfig` / `EmbedConfigSchema` | Endpoint, model, and optional knobs |
-| `EmbedOptions` | Harness deps plus optional retry, `Retry-After` override, abort |
-| `runJSONRequest` | Classified, retried JSON POST (sibling clients reuse this) |
-| `extractRetryAfterMs` | Default `Retry-After` reader (seconds or HTTP-date) |
-| `ModelRequestError` | Transport, HTTP, or non-JSON 200 — `reason` is the classified `InferenceError` |
+| `EmbedOptions` | Optional harness deps, retry, `Retry-After` override, abort |
+| `RequestDependencies` / `RetryAfterExtractor` | Types of the `EmbedOptions` fields |
+| `EmbeddingRequestError` | Every request failure — `reason` is the classified `InferenceError` |
+
+The JSON transport (`runJSONRequest`) is private.
 
 Quickstart shape (matches the README):
 
 ```ts
-import { createDefaultScheduler } from "@intx/inference";
-import { embedTexts, probeEmbedDims } from "@corbits/embedding";
-
-const deps = { fetch, scheduler: createDefaultScheduler() };
-const [vector] = await embedTexts(
-  ["hello world"],
-  { baseURL: "http://localhost:11434/v1", model: "nomic-embed-text" },
-  { deps },
-);
+import { embedTexts } from "@corbits/embedding";
+
+const [vector] = await embedTexts(["hello world"], {
+  baseURL: "http://localhost:11434/v1",
+  model: "nomic-embed-text",
+});
 ```
 
-`probeEmbedDims(config, { deps })` is the same config and deps; it is not a
+`probeEmbedDims(config)` is the same config and options; it is not a
 separate protocol.
 
 ## Request dependencies
 
 The transport reads only `fetch` and `scheduler` from the harness
-(`RequestDependencies`). That is deliberately narrower than Interchange
+(`RequestDependencies`), defaulting to global `fetch` and
+`createDefaultScheduler()`. That is deliberately narrower than Interchange
 `Dependencies`, whose `adapters` registry a caller should not have to
 assemble in order to embed a string. A real `Dependencies` still satisfies
 the pick structurally.
@@ -88,20 +87,22 @@ and `createDefaultRetryPolicy` (back off retryables, abort the rest). A 429
 is therefore classified and backed off as a chat 429 would be; a
 `credential_failure` aborts immediately.
 
-`runJSONRequest` is duplicated, modulo comments, in `@corbits/reranking`. It
-is not shared infrastructure yet — the intended home is `@intx/inference` as
-a non-streaming sibling of `runInference`. Until then, `ModelRequestError` is
-a distinct class in each package: `instanceof` does not hold across the two.
-Catch on `error.name === "ModelRequestError"`.
+Following Interchange, the `InferenceError` is carried as data on a thrown
+`Error` subclass (`EmbeddingRequestError`), never thrown itself.
+
+`runJSONRequest` is duplicated, modulo comments, in `@corbits/reranking`,
+which still throws its own `ModelRequestError`; code using both packages
+checks two error classes. The intended home for the transport is
+`@intx/inference`, as a non-streaming sibling of `runInference`.
 
 ## Failure modes
 
 - Transport, HTTP status, or a 200 whose body is not JSON →
-  `ModelRequestError` with classified `reason` and the URL.
-- Malformed embeddings JSON, wrong count, bad index → thrown `Error` (not
-  `ModelRequestError`); the protocol succeeded, the payload did not.
-- `batchSize` not an integer `>= 1` → `RangeError` before any request
-  (`i += size` of 0 would never advance).
+  `EmbeddingRequestError` with classified `reason` and the URL.
+- Malformed embeddings JSON, wrong count, bad index →
+  `EmbeddingRequestError` with a `classifyProtocolMismatch` reason.
+- Config failing `EmbedConfigSchema` (e.g. `batchSize` not an integer
+  `>= 1`) → arktype `TraversalError` before any request.
 - Empty `texts` → `[]`, no request.
 - Caller `signal` or per-attempt timeout (default 30s) abort the attempt;
   aborting mid-delay wakes immediately and the next attempt fails its
 
@@ -80,8 +80,8 @@ Reply: `{ data: { index: number, embedding: number[] | string }[] }`.
 Base64 strings decode with `atob` → `Uint8Array` → little-endian
 `Float32Array` → `number[]`.
 
-`embedTexts` also range-checks `batchSize` at runtime so a value that
-bypassed the schema cannot stall `batches` (`i += size`).
+`embedTexts` asserts `config` against `EmbedConfigSchema` first, so a
+`batchSize` below 1 cannot stall `batches` (`i += size`).
 
 ## Errors and retry
 
@@ -92,16 +92,13 @@ bypassed the schema cannot stall `batches` (`i += size`).
 3. network throw → `classifyNetworkError` or `classifyAbortError`
 4. JSON parse fail → `classifyProtocolMismatch`
 5. `retryPolicy` (default `createDefaultRetryPolicy`) → `abort` throws
-   `ModelRequestError`, else sleep `delayMs` on `deps.scheduler`
+   `EmbeddingRequestError`, else sleep `delayMs` on `deps.scheduler`
 
 `extractRetryAfterMs` reads `Retry-After` as seconds or HTTP-date, clamped
 at zero. Callers override via `EmbedOptions.extractRetryAfterMs` (same
 signature as Interchange's unexported extractor; re-declared so this
 package depends only on the published surface).
 
-`ModelRequestError.name` is `"ModelRequestError"`. Discriminate on the
-name when catching both this package and `@corbits/reranking`.
-
 ## Tests
 
 `bun run test` is `bun test ./src`. Coverage is the client contract: empty
 
@@ -73,16 +73,7 @@ scheduler), with optional `retryPolicy`, `extractRetryAfterMs`, and `signal`.
 
 ## Errors
 
-Every failure mode — transport, HTTP status, or a 200 with an unexpected body — raises `ModelRequestError`, carrying the classified `InferenceError` as `reason` plus the request URL. The embedding and reranking packages each carry their own copy of this class while the shared transport is upstreamed, so code catching both discriminates on `error.name === "ModelRequestError"`.
-
-## Lower-level: transport
-
-The barrel also re-exports the one-shot JSON transport `embedTexts` is built on, for sibling clients that want the same classified, retried request path:
-
-- `runJSONRequest` — one JSON POST with error classification and retry.
-- `extractRetryAfterMs` — default `Retry-After` reader, overridable per call.
-- `ModelRequestError` — error for every failure mode, with `reason` and URL.
-- Types `RunRequestOptions` and `RetryAfterExtractor`.
+Every request failure — transport, HTTP status, or a 200 with an unexpected body — throws `EmbeddingRequestError` (`extends Error`), carrying the classified `InferenceError` as `reason` and the request `url`. A config that fails `EmbedConfigSchema` throws arktype's `TraversalError` before any request.
 
 ## Interchange
 
 
@@ -8,7 +8,7 @@ import {
   EmbedConfigSchema,
   type EmbedConfig,
 } from "./embed";
-import { extractRetryAfterMs, ModelRequestError } from "./request";
+import { EmbeddingRequestError } from "./request";
 
 const CONFIG: EmbedConfig = {
   baseURL: "https://embed.example/v1",
@@ -134,12 +134,12 @@ describe("embedTexts", () => {
   it("rejects a batchSize that is not an integer >= 1 instead of looping forever", async () => {
     // `batches` advances by `i += size`, so a size of 0 never advances and
     // grows the batch list until OOM. Fractional sizes would also stall or
-    // slice wrongly. Schema and runtime both require integer >= 1.
+    // slice wrongly. The schema requires integer >= 1.
     for (const batchSize of [0, -1, 0.5, Number.NaN, 1.5]) {
       const { deps: d, calls } = deps([embedding(3)]);
       await expect(
         embedTexts(["a"], { ...CONFIG, batchSize }, { deps: d }),
-      ).rejects.toBeInstanceOf(RangeError);
+      ).rejects.toThrow(/batchSize/);
       expect(calls).toHaveLength(0);
     }
   });
@@ -148,9 +148,9 @@ describe("embedTexts", () => {
     const { deps: d } = deps([
       Response.json({ data: [{ index: 0, embedding: true }] }),
     ]);
-    await expect(embedTexts(["a"], CONFIG, { deps: d })).rejects.toThrow(
-      /malformed embeddings response/,
-    );
+    const rejection = expect(embedTexts(["a"], CONFIG, { deps: d })).rejects;
+    await rejection.toBeInstanceOf(EmbeddingRequestError);
+    await rejection.toThrow(/malformed embeddings response/);
   });
 });
 
@@ -195,7 +195,7 @@ describe("retry behaviour inherited from the inference policy", () => {
       new Response("unauthorized", { status: 401 }),
     ]);
     await expect(embedTexts(["a"], CONFIG, { deps: d })).rejects.toBeInstanceOf(
-      ModelRequestError,
+      EmbeddingRequestError,
     );
     expect(calls).toHaveLength(1);
   });
@@ -232,21 +232,6 @@ describe("retry-after handling", () => {
     });
     expect(seen).toEqual(["7"]);
   });
-
-  it("reads the seconds form and tolerates an absent header", () => {
-    expect(extractRetryAfterMs(new Headers({ "retry-after": "2" }))).toBe(
-      2_000,
-    );
-    expect(extractRetryAfterMs(new Headers())).toBeUndefined();
-  });
-
-  it("never returns a negative delay for a date already past", () => {
-    expect(
-      extractRetryAfterMs(
-        new Headers({ "retry-after": "Wed, 21 Oct 2015 07:28:00 GMT" }),
-      ),
-    ).toBeGreaterThanOrEqual(0);
-  });
 });
 
 describe("reply integrity", () => {
@@ -319,7 +304,7 @@ describe("transport failure modes", () => {
       }),
     ]);
     await expect(embedTexts(["a"], CONFIG, { deps: d })).rejects.toBeInstanceOf(
-      ModelRequestError,
+      EmbeddingRequestError,
     );
   });
 
@@ -347,7 +332,7 @@ describe("transport failure modes", () => {
         { ...CONFIG, timeoutMs: 5 },
         { deps: d, signal: controller.signal },
       ),
-    ).rejects.toBeInstanceOf(ModelRequestError);
+    ).rejects.toBeInstanceOf(EmbeddingRequestError);
     expect(calls).toHaveLength(1);
   });
 });