Remove direct POSTGRES_DATABASE_URL fallback; Postgres via Hyperdrive only (#351)

The Worker now connects to Postgres exclusively through the HYPERDRIVE
binding. Local dev uses the binding's localConnectionString (committed in
wrangler.jsonc, pointing at the throwaway Docker Postgres from
docs/LOCAL_POSTGRES.md) instead of a POSTGRES_DATABASE_URL Worker var.

Closes the Codex finding about unpooled direct connections from deployed
Workers: the not-recommended direct-connection config is no longer possible.
POSTGRES_DATABASE_URL remains as a Node-side env var for drizzle-kit and
the D1->Postgres migration script only.

docs/LOCAL_POSTGRES.md

@@ -54,13 +54,23 @@ POSTGRES_DATABASE_URL=postgres://openseo:openseo@localhost:5433/openseo \
 
 ## 3. Point the app at Postgres
 
-The Cloudflare Vite runtime reads Worker vars from `.env.local`, so set both
+The Cloudflare Vite runtime reads Worker vars from `.env.local`, so set the
-values there (not just in your shell):
+provider flag there (not just in your shell):
 
 ```sh
 # .env.local
 DATABASE_PROVIDER=postgres
-POSTGRES_DATABASE_URL=postgres://openseo:openseo@localhost:5433/openseo
+```
+
+The connection string comes from the `HYPERDRIVE` binding: in local dev,
+miniflare resolves it to the `localConnectionString` committed in
+`wrangler.jsonc`, which already points at the Docker container from step 1.
+(In deployed Workers the same binding resolves to real Hyperdrive — the app
+never connects to Postgres except through this binding.) If your local Postgres
+lives elsewhere, override without touching the config:
+
+```sh
+CLOUDFLARE_HYPERDRIVE_LOCAL_CONNECTION_STRING_HYPERDRIVE=postgres://... pnpm dev
 ```
 
 Then start the dev server as usual:
@@ -69,9 +79,13 @@ Then start the dev server as usual:
 pnpm dev
 ```
 
-To switch back to D1, remove those two lines (or set `DATABASE_PROVIDER=d1`) and
+To switch back to D1, remove that line (or set `DATABASE_PROVIDER=d1`) and
 restart.
 
+> `POSTGRES_DATABASE_URL` (step 2) is only read by Node-side tooling —
+> `drizzle-kit` and `scripts/migrate-d1-to-postgres.ts`. The app itself ignores
+> it.
+
 ## 4. Verify
 
 ```sh

runbooks/d1-to-postgres-detailed.md

@@ -83,7 +83,8 @@ after cutover would collide with migrated rows.
    Confirm it ends with **"All row counts match."**
 
 3. **Cut over.** Point the deployment at Postgres (`DATABASE_PROVIDER=postgres`
-   plus a Hyperdrive binding or `POSTGRES_DATABASE_URL`) and deploy:
+   plus a Hyperdrive binding — the app only connects to Postgres through
+   Hyperdrive) and deploy:
 
    ```sh
    pnpm deploy:postgres

runbooks/d1-to-postgres-simple.md

@@ -63,8 +63,8 @@ during the window is expected — see the detailed runbook.)
 ## 6. Cut over
 
 Point the deployment at Postgres (`DATABASE_PROVIDER=postgres` plus a Hyperdrive
-binding or `POSTGRES_DATABASE_URL`) and deploy, then smoke-test (load a project,
+binding — the app only connects to Postgres through Hyperdrive) and deploy, then
-save a keyword, check billing):
+smoke-test (load a project, save a keyword, check billing):
 
 ```sh
 pnpm deploy:postgres

src/db/pg/client.ts

@@ -57,9 +57,7 @@ export const pgDb = new Proxy(
  * stale-connection risk) and do NOT call `sql.end()`: the Workers↔Hyperdrive
  * socket is torn down automatically when the invocation ends, and the pooled
  * origin connection stays warm for reuse. Not ending it also means a streamed
- * response can keep querying after the handler returns. (Without a Hyperdrive
+ * response can keep querying after the handler returns.
- * binding, `POSTGRES_DATABASE_URL` opens a direct connection that the Workers
- * runtime still reclaims at invocation end.)
  */
 export async function withPgClient<T>(fn: () => Promise<T>): Promise<T> {
   if (getDatabaseProvider() !== "postgres") {

src/db/provider.ts

@@ -18,6 +18,10 @@ export function getDatabaseProvider(): DatabaseProvider {
   );
 }
 
+// Postgres is only reachable through the HYPERDRIVE binding — never a direct
+// connection string from a Worker var. In local dev the binding resolves to
+// `localConnectionString` from wrangler.jsonc (miniflare never contacts real
+// Hyperdrive), so the same code path covers both.
 export function getPostgresConnectionString() {
   const hyperdrive = Reflect.get(env, "HYPERDRIVE") as
     | { connectionString?: string }
@@ -27,12 +31,7 @@ export function getPostgresConnectionString() {
     return hyperdriveUrl;
   }
 
-  const directUrl = Reflect.get(env, "POSTGRES_DATABASE_URL");
-  if (typeof directUrl === "string" && directUrl.trim()) {
-    return directUrl.trim();
-  }
-
   throw new Error(
-    "DATABASE_PROVIDER=postgres requires a HYPERDRIVE binding or POSTGRES_DATABASE_URL.",
+    "DATABASE_PROVIDER=postgres requires a HYPERDRIVE binding (in local dev, its localConnectionString).",
   );
 }

src/env.d.ts

@@ -21,7 +21,6 @@ declare namespace Cloudflare {
     BETTER_AUTH_SECRET?: string;
     BETTER_AUTH_URL?: string;
     DATABASE_PROVIDER?: "d1" | "postgres";
-    POSTGRES_DATABASE_URL?: string;
     HYPERDRIVE?: {
       connectionString: string;
     };

wrangler.jsonc

@@ -78,15 +78,23 @@
   // a worker *secret* (`wrangler secret put DATABASE_PROVIDER` -> "postgres") so it
   // survives `wrangler deploy` — which resets plain vars/bindings and is what
   // reverted prod to the D1 default before. This Hyperdrive binding points the
-  // pooled connection at that Postgres. Without Hyperdrive, POSTGRES_DATABASE_URL
+  // pooled connection at that Postgres. Hyperdrive is the ONLY way the app
-  // is the direct-connection fallback (no edge pooling/caching).
+  // connects to Postgres — there is no direct-connection fallback.
+  //
+  // `localConnectionString` is local-dev only (ignored by `wrangler deploy`):
+  // it's the throwaway Docker Postgres from docs/LOCAL_POSTGRES.md, and nothing
+  // connects to it unless DATABASE_PROVIDER=postgres is set in .env.local.
   //
   // SELF-HOSTERS on the free D1 default: DELETE this hyperdrive block before
   // deploying. The id below lives in OpenSEO's Cloudflare account, so `wrangler
   // deploy` will fail without access to it. D1 stays the default when
   // DATABASE_PROVIDER is unset.
   "hyperdrive": [
-    { "binding": "HYPERDRIVE", "id": "9d64ccfb559f44449ce52a143912f898" },
+    {
+      "binding": "HYPERDRIVE",
+      "id": "9d64ccfb559f44449ce52a143912f898",
+      "localConnectionString": "postgres://openseo:openseo@localhost:5433/openseo",
+    },
   ],
   "r2_buckets": [
     {