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packages/api-stack/api/api-plugin-vault/src/routes/build-routes.md

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+# routes/build-routes
+
+<!-- begin:auto-docs -->
+_(no submodules)_
+<!-- end:auto-docs -->
+
+## Purpose
+
+Builds the 5 OpenAPI route entries that `createVaultPlugin` mounts on
+the host's Hono app: list, create, read, update, delete. Each entry is
+a `PluginRouteEntry` — a `RouteConfig` plus a handler — with full Zod
+inference through the `RouteBuilder` chain. The OpenAPI document and
+the runtime routing surface cannot drift because both are produced from
+the same builder output.
+
+## Features
+
+- Five routes — `GET /vault/items`, `POST /vault/items`,
+  `GET /vault/items/:id`, `PATCH /vault/items/:id`,
+  `DELETE /vault/items/:id` — each tagged `vault` for grouped doc
+  display.
+- Per-handler upstream `requireAuth()` invocation — every route is
+  gated; anonymous calls produce `AUTH_UNAUTHENTICATED` (401) via the
+  auth plugin's middleware.
+- Per-request open/close lifecycle: every route opens the principal's
+  vault via `vaultService.openForPrincipal`, performs the operation,
+  and closes the handle in `finally` so the vault is locked again
+  before the response returns.
+- Anti-enumeration policy baked in: any reference to an item id that
+  does not exist OR is owned by another principal raises
+  `VAULT_PLUGIN_ITEM_NOT_FOUND` (404) — NEVER 403. This prevents an
+  attacker from probing the existence of item ids owned by other
+  principals.
+- Size enforcement at the handler boundary, not at the Zod schema, so
+  the error message can include the exact byte count and the configured
+  `maxItemSizeBytes`.
+- 4 OTel counters + 1 histogram emitted per operation (success +
+  failure outcomes).
+
+## Usage: Basic
+
+```ts
+import { buildVaultRoutes } from "@suaveplan/api-plugin-vault";
+
+const entries = buildVaultRoutes(vaultService, config);
+definePluginRoutes(entries, {
+    app,
+    registry: openAPIRegistry,
+    pluginName: "vault",
+});
+```
+
+## Usage: Advanced
+
+```ts
+// Drop one of the 5 routes by filtering before registration — operators
+// running a read-only mirror can elide the mutation routes.
+const entries = buildVaultRoutes(vaultService, config).filter((e) =>
+    e.route.method === "get"
+);
+definePluginRoutes(entries, { app, registry, pluginName: "vault" });
+```
+
+## API Reference
+
+### `buildVaultRoutes(vaultService, config): PluginRouteEntry[]`
+
+Returns 5 entries in registration order: list, create, get, update,
+delete. Every entry has:
+
+- `route` — a built `RouteConfig` carrying the full Zod schema chain.
+- `handler` — async function taking a Hono `Context` and returning
+  `Promise<Response>`.
+
+The handler wraps the actual operation in a `requireAuth()` gate; the
+auth plugin's `Principal` is read from `c.get("user")`.
+
+## Implementation Notes
+
+- The `RouteBuilder` `.params(VaultItemParamsSchema)` registers the
+  `{id}` URL parameter on the OpenAPI doc using the OpenAPI convention
+  (`{id}`); Hono's runtime router consumes the same builder output, so
+  the path matches both surfaces.
+- The handler explicitly normalises the wire envelope: every success
+  response is `{ success: true, data }` (list also includes
+  `meta: { total }`). The shared error envelope is contributed by the
+  `StandardResponses` block from `@suaveplan/api-openapi` — handlers
+  never construct an error envelope themselves; they `throw` a
+  `VaultPluginError` and let the host's error-handler middleware
+  serialise it.
+- `Buffer.byteLength(body, "utf8")` is used for size enforcement so
+  the byte count matches what an HTTP client would actually transmit
+  (rather than the JavaScript string `length` which counts UTF-16
+  code units).
+- The defensive null-check on `c.get("user")` inside `withOpenVault`
+  exists because `requireAuth()` runs in a separate middleware step
+  and TypeScript cannot narrow across the await boundary. Production
+  cannot reach the branch (requireAuth has already thrown), but the
+  branch is reachable from unit tests that bypass the guard.
+- Coverage note: the `requireAuthThen` `response === undefined` branch
+  exists for TypeScript narrowing; the unit tests assert it raises
+  `VAULT_PLUGIN_FORBIDDEN` by injecting a stubbed `requireAuth` that
+  returns without invoking `next`.