docs(chat): DX-bar JSDoc on AgentError/toAgentError/isAbortError (per-kind docs + @example) (#704)

Brings the newly-shipped error-UX public symbols up to the DX-pass bar:
document each AgentErrorKind + retryability, add an @example to AgentError
(reading kind/retryable in a catch) and to toAgentError (classifying HTTP 500),
and @param/@returns on the classifier + isAbortError.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: blove

apps/website/content/docs/chat/api/api-docs.json

@@ -1429,7 +1429,7 @@
   {
     "name": "AgentError",
     "kind": "class",
-    "description": "Structured, classified failure surfaced on `Agent.error`. Extends `Error`\n so existing `.message` / `instanceof Error` reads keep working.",
+    "description": "Structured, classified failure surfaced on `Agent.error`. Extends `Error`, so\nexisting `.message` / `instanceof Error` reads keep working — but adds a\nmachine-readable AgentErrorKind, a `retryable` flag, an optional HTTP\n`status`, and the original `cause`.\n\nYou rarely construct one yourself; adapters normalize raw failures via\ntoAgentError. Read it off the agent to render legible, cause-specific UI:",
     "params": [
       {
         "name": "init",
@@ -1438,18 +1438,20 @@
         "optional": false
       }
     ],
-    "examples": [],
+    "examples": [
+      "```ts\nconst err = agent.error();            // AgentError | undefined\nif (err) {\n  console.warn(err.message);          // legible, per-kind copy\n  if (err.kind === 'auth') showApiKeyHelp();\n  if (err.retryable) showRetryButton(); // → agent.retry()\n}\n```"
+    ],
     "properties": [
       {
         "name": "cause",
         "type": "unknown",
-        "description": "",
+        "description": "The original raw error this was classified from, preserved for debugging/telemetry.",
         "optional": false
       },
       {
         "name": "kind",
         "type": "AgentErrorKind",
-        "description": "",
+        "description": "The classified failure type. See AgentErrorKind.",
         "optional": false
       },
       {
@@ -1467,7 +1469,7 @@
       {
         "name": "retryable",
         "type": "boolean",
-        "description": "connection | server | interrupted → true; auth | aborted | non-auth-4xx → false.",
+        "description": "Whether retrying the same request could plausibly succeed:\n `connection` | `server` (5xx) | `interrupted` → true; `auth` | `aborted` | non-auth `4xx` → false.",
         "optional": false
       },
       {
@@ -1479,7 +1481,7 @@
       {
         "name": "status",
         "type": "number",
-        "description": "",
+        "description": "The HTTP status code when the failure came from an HTTP response.",
         "optional": true
       }
     ],
@@ -7102,7 +7104,7 @@
   {
     "name": "AgentErrorKind",
     "kind": "type",
-    "description": "",
+    "description": "The failure class of an AgentError, used to drive UI and retry logic:\n\n- `connection` — offline / DNS / connection refused / `fetch` failed. Retryable.\n- `auth` — `401` / `403`; credentials or API key are wrong. Not retryable.\n- `server` — a `5xx` (retryable) or a non-auth `4xx` like `400`/`404`/`429` (not retryable).\n- `interrupted` — the stream closed mid-response after a run had started. Retryable.\n- `aborted` — the user pressed stop; treated as a graceful idle, not surfaced as an error.",
     "signature": "\"connection\" | \"auth\" | \"server\" | \"interrupted\" | \"aborted\"",
     "examples": []
   },
@@ -7263,7 +7265,7 @@
   {
     "name": "AGENT_ERROR_MESSAGES",
     "kind": "const",
-    "description": "Default human-facing copy per kind.",
+    "description": "Default, human-facing copy per AgentErrorKind. Used as the message when\na classified error has no better text. Override by mapping `error.kind` to your\nown strings in a custom error component.",
     "signature": "Record<AgentErrorKind, string>",
     "examples": []
   },
@@ -7725,13 +7727,13 @@
   {
     "name": "isAbortError",
     "kind": "function",
-    "description": "True when `raw` represents a user-requested abort. Shared by adapters + classifier.",
+    "description": "Whether `raw` represents an abort (a `DOMException`/`Error` named `AbortError`,\nor an abort-ish message). Shared by the runtime adapters and toAgentError\nso a user-requested stop settles to idle instead of surfacing as an error.",
     "signature": "isAbortError(raw: unknown): boolean",
     "params": [
       {
         "name": "raw",
         "type": "unknown",
-        "description": "",
+        "description": "Any thrown/rejected value.",
         "optional": false
       }
     ],
@@ -8047,21 +8049,23 @@
   {
     "name": "toAgentError",
     "kind": "function",
-    "description": "Classify any raw error into a structured AgentError. Idempotent.",
+    "description": "Classify any raw error into a structured AgentError.\n\nResolution order (first match wins): an existing `AgentError` is returned\nunchanged (idempotent) → a user abort → a structured `status`/`cause.status`\n→ network/connection markers → an HTTP-shaped status in the message → a\n`server` + retryable fallback. The original error is always preserved on\n`cause`. Runtime adapters call this before setting `Agent.error`; custom\nbackends can call it too (or throw an `AgentError` directly).",
     "signature": "toAgentError(raw: unknown): AgentError<>",
     "params": [
       {
         "name": "raw",
         "type": "unknown",
-        "description": "",
+        "description": "Any thrown/rejected value — an `Error`, a `{ status }` object, a string, etc.",
         "optional": false
       }
     ],
     "returns": {
       "type": "AgentError<>",
       "description": ""
     },
-    "examples": []
+    "examples": [
+      "```ts\nconst e = toAgentError(new Error('HTTP 500: Internal Server Error'));\ne.kind;      // 'server'\ne.retryable; // true\ne.status;    // 500\n```"
+    ]
   },
   {
     "name": "toClientToolSpecs",

libs/chat/src/lib/agent/agent-error.ts

@@ -1,13 +1,44 @@
 // SPDX-License-Identifier: MIT
+
+/**
+ * The failure class of an {@link AgentError}, used to drive UI and retry logic:
+ *
+ * - `connection` — offline / DNS / connection refused / `fetch` failed. Retryable.
+ * - `auth` — `401` / `403`; credentials or API key are wrong. Not retryable.
+ * - `server` — a `5xx` (retryable) or a non-auth `4xx` like `400`/`404`/`429` (not retryable).
+ * - `interrupted` — the stream closed mid-response after a run had started. Retryable.
+ * - `aborted` — the user pressed stop; treated as a graceful idle, not surfaced as an error.
+ */
 export type AgentErrorKind = 'connection' | 'auth' | 'server' | 'interrupted' | 'aborted';
 
-/** Structured, classified failure surfaced on `Agent.error`. Extends `Error`
- *  so existing `.message` / `instanceof Error` reads keep working. */
+/**
+ * Structured, classified failure surfaced on `Agent.error`. Extends `Error`, so
+ * existing `.message` / `instanceof Error` reads keep working — but adds a
+ * machine-readable {@link AgentErrorKind}, a `retryable` flag, an optional HTTP
+ * `status`, and the original `cause`.
+ *
+ * You rarely construct one yourself; adapters normalize raw failures via
+ * {@link toAgentError}. Read it off the agent to render legible, cause-specific UI:
+ *
+ * @example
+ * ```ts
+ * const err = agent.error();            // AgentError | undefined
+ * if (err) {
+ *   console.warn(err.message);          // legible, per-kind copy
+ *   if (err.kind === 'auth') showApiKeyHelp();
+ *   if (err.retryable) showRetryButton(); // → agent.retry()
+ * }
+ * ```
+ */
 export class AgentError extends Error {
+  /** The classified failure type. See {@link AgentErrorKind}. */
   readonly kind: AgentErrorKind;
-  /** connection | server | interrupted → true; auth | aborted | non-auth-4xx → false. */
+  /** Whether retrying the same request could plausibly succeed:
+   *  `connection` | `server` (5xx) | `interrupted` → true; `auth` | `aborted` | non-auth `4xx` → false. */
   readonly retryable: boolean;
+  /** The HTTP status code when the failure came from an HTTP response. */
   readonly status?: number;
+  /** The original raw error this was classified from, preserved for debugging/telemetry. */
   override readonly cause: unknown;
 
   constructor(init: { kind: AgentErrorKind; message: string; retryable: boolean; status?: number; cause?: unknown }) {
@@ -20,7 +51,11 @@ export class AgentError extends Error {
   }
 }
 
-/** Default human-facing copy per kind. */
+/**
+ * Default, human-facing copy per {@link AgentErrorKind}. Used as the message when
+ * a classified error has no better text. Override by mapping `error.kind` to your
+ * own strings in a custom error component.
+ */
 export const AGENT_ERROR_MESSAGES: Record<AgentErrorKind, string> = {
   connection: "Can't reach the server. Check your connection and try again.",
   auth: 'Authentication failed. Check your API key or credentials.',

libs/chat/src/lib/agent/to-agent-error.ts

@@ -1,7 +1,14 @@
 // SPDX-License-Identifier: MIT
 import { AgentError, AGENT_ERROR_MESSAGES, type AgentErrorKind } from './agent-error';
 
-/** True when `raw` represents a user-requested abort. Shared by adapters + classifier. */
+/**
+ * Whether `raw` represents an abort (a `DOMException`/`Error` named `AbortError`,
+ * or an abort-ish message). Shared by the runtime adapters and {@link toAgentError}
+ * so a user-requested stop settles to idle instead of surfacing as an error.
+ *
+ * @param raw Any thrown/rejected value.
+ * @returns `true` if it looks like an abort.
+ */
 export function isAbortError(raw: unknown): boolean {
   return raw instanceof Error && (raw.name === 'AbortError' || /\babort/i.test(raw.message));
 }
@@ -63,7 +70,26 @@ function classifyByStatus(status: number, raw: unknown): AgentError {
   return make('server', true, raw, undefined, 'Something went wrong. You can try again.');
 }
 
-/** Classify any raw error into a structured {@link AgentError}. Idempotent. */
+/**
+ * Classify any raw error into a structured {@link AgentError}.
+ *
+ * Resolution order (first match wins): an existing `AgentError` is returned
+ * unchanged (idempotent) → a user abort → a structured `status`/`cause.status`
+ * → network/connection markers → an HTTP-shaped status in the message → a
+ * `server` + retryable fallback. The original error is always preserved on
+ * `cause`. Runtime adapters call this before setting `Agent.error`; custom
+ * backends can call it too (or throw an `AgentError` directly).
+ *
+ * @param raw Any thrown/rejected value — an `Error`, a `{ status }` object, a string, etc.
+ * @returns The classified {@link AgentError} (kind, retryable, status?, cause).
+ * @example
+ * ```ts
+ * const e = toAgentError(new Error('HTTP 500: Internal Server Error'));
+ * e.kind;      // 'server'
+ * e.retryable; // true
+ * e.status;    // 500
+ * ```
+ */
 export function toAgentError(raw: unknown): AgentError {
   if (raw instanceof AgentError) return raw;
   if (isAbortError(raw)) return make('aborted', false, raw);