refactor(msg-bus): prefer explicit enum on AsyncAPI error

frontend/src/lib/generated/message-bus/RtErrorCode.ts

@@ -1,14 +0,0 @@
-enum RtErrorCode {
-	MINUS_32001 = -32001,
-	MINUS_32002 = -32002,
-	MINUS_32003 = -32003,
-	MINUS_32004 = -32004,
-	MINUS_32005 = -32005,
-	MINUS_32006 = -32006,
-	MINUS_32007 = -32007,
-	MINUS_32603 = -32603,
-	MINUS_32600 = -32600,
-	MINUS_32601 = -32601,
-	MINUS_32602 = -32602
-}
-export type { RtErrorCode as default };

frontend/src/lib/generated/message-bus/RtErrorObject.ts

@@ -1,9 +1,8 @@
-import type RtErrorCode from './RtErrorCode';
 import type RtErrorMessage from './RtErrorMessage';
 // AUTO-GENERATED — do not edit by hand.
 // Regenerate with `just asyncapi-ts`.
 interface RtErrorObject {
-	code: RtErrorCode;
+	code: number;
 	data?: unknown;
 	message: RtErrorMessage;
 }

frontend/src/lib/message-bus/error-codes.ts

@@ -0,0 +1,55 @@
+// Named constants for JSON-RPC 2.0 error codes emitted on the message-bus
+// WebSocket wire. Mirrors `application/ports/message_bus_ports.rs::error_code`
+// on the server — the Rust module is the source of truth.
+//
+// Hand-written, deliberately not generated: Modelina projects a JSON-Schema
+// `enum` of numeric values into a TS enum with mangled member names
+// (`MINUS_32001 = -32001`), which reads worse than no enum at all. The wire
+// type is just `number`; readable name-to-code lookup lives here.
+//
+// Values are frozen across releases — a new denial cause gets a new value,
+// never repurposes an existing one. Adding a code: bump the Rust module and
+// this file in the same commit; the wire spec's description text is a
+// derivative of the Rust constants (see `generate-asyncapi.rs`).
+
+/**
+ * Application-defined codes live in the JSON-RPC 2.0 server-defined range
+ * `-32099..-32000`; standard envelope codes live in `-32700..-32600`.
+ */
+export const RtErrorCode = {
+	// ── Application-defined (subscribe / edit path denials) ─────────────
+	/** Resource-scoped topic, caller lacks Read on the resource (or the
+	 *  resource does not exist — the two outcomes are indistinguishable to
+	 *  the caller by design, to preserve anti-enumeration). */
+	NO_READ: -32001,
+	/** Resource-scoped topic requires Share, caller has Read but not Share.
+	 *  Applies to `file:{id}:shares` (Phase B). */
+	NO_SHARE: -32002,
+	/** Resource-scoped topic requires Comment (`file:{id}:comments`, Phase B). */
+	NO_COMMENT: -32003,
+	/** Identity-scoped mismatch, OR unknown/malformed topic. Same wire code
+	 *  regardless of whether the target exists — anti-enum. */
+	TOPIC_FORBIDDEN: -32004,
+	/** Per-connection subscription cap hit. */
+	SUB_LIMIT: -32005,
+	/** Subscribe-frame token bucket exhausted. */
+	RATE_LIMITED: -32006,
+	/** CRDT edit frame from a caller without Edit on the doc. Emitted as an
+	 *  `rt.write_denied` notification (not tied to a request id). */
+	NO_EDIT: -32007,
+
+	// ── JSON-RPC 2.0 standard envelope codes ────────────────────────────
+	/** Server-side failure the client should retry. */
+	INTERNAL_ERROR: -32603,
+	/** Malformed JSON-RPC envelope (missing `method`, wrong `jsonrpc` version). */
+	INVALID_REQUEST: -32600,
+	/** Method outside the `rt.*` allow-list. */
+	METHOD_NOT_FOUND: -32601,
+	/** Method known but `params` shape wrong (missing `topic`, unparseable). */
+	INVALID_PARAMS: -32602
+} as const satisfies Record<string, number>;
+
+/** Union of every named code's numeric value. Narrows a bare `number` on
+ *  `RtErrorObject.code` to the eleven known literals for exhaustive
+ *  `switch` blocks. */
+export type RtErrorCodeValue = (typeof RtErrorCode)[keyof typeof RtErrorCode];

src/bin/generate-asyncapi.rs

@@ -473,10 +473,30 @@ fn rpc_error_object_schema() -> Value {
 }
 
 fn rpc_error_code_schema() -> Value {
-    json!({
+    // Kept as plain `integer` — Modelina projects a JSON-Schema `enum` of
-        "type": "integer",
+    // numeric values into a TS enum with mangled member names
-        "description": "Stable integer error code. Values are frozen across releases — a new denial cause gets a new value, never repurposes an existing one.",
+    // (`MINUS_32001 = -32001`), which is worse than no enum at all. The
-        "enum": [
+    // Rust `error_code` module is the source of truth for named
+    // constants; the FE mirrors it in `frontend/src/lib/message-bus/
+    // error-codes.ts` (hand-written, 11 lines, sits alongside the
+    // generated DTOs). Description enumerates the full set inline so the
+    // AsyncAPI spec is still self-documenting.
+    let full_description = format!(
+        "Stable integer error code. Values are frozen across releases — a \
+         new denial cause gets a new value, never repurposes an existing \
+         one. Application-defined codes ({}..={}):\n\
+         · {} NO_READ — resource-scoped topic, caller lacks Read (or \
+         resource doesn't exist — indistinguishable by design)\n\
+         · {} NO_SHARE — resource requires Share, caller has Read but not Share\n\
+         · {} NO_COMMENT — resource requires Comment\n\
+         · {} TOPIC_FORBIDDEN — identity-scoped mismatch or unknown/malformed topic\n\
+         · {} SUB_LIMIT — per-connection subscription cap hit\n\
+         · {} RATE_LIMITED — subscribe-frame token bucket exhausted\n\
+         · {} NO_EDIT — CRDT edit frame from a caller without Edit\n\
+         Standard JSON-RPC 2.0 codes:\n\
+         · {} INTERNAL_ERROR · {} INVALID_REQUEST · {} METHOD_NOT_FOUND · {} INVALID_PARAMS",
+        -32099,
+        -32000,
         error_code::NO_READ,
         error_code::NO_SHARE,
         error_code::NO_COMMENT,
@@ -488,7 +508,10 @@ fn rpc_error_code_schema() -> Value {
         error_code::INVALID_REQUEST,
         error_code::METHOD_NOT_FOUND,
         error_code::INVALID_PARAMS,
-        ],
+    );
+    json!({
+        "type": "integer",
+        "description": full_description,
     })
 }