From 214a1b5909b7bf232a969c43e12268e102c1d1cf Mon Sep 17 00:00:00 2001
From: Eric Luce <37158449+eluce2@users.noreply.github.com>
Date: Sat, 31 Jan 2026 13:04:59 -0600
Subject: [PATCH] fix(typegen): convert list-tables endpoint from GET to POST

Prevents 431 Request Header Fields Too Large when config grows.
Passes config as JSON body instead of query param, matching
test-connection and table-metadata endpoints.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 .changeset/list-tables-post.md                |  5 ++
 packages/typegen/src/server/app.ts            | 64 ++++++++++---------
 .../typegen/web/src/hooks/useListTables.ts    |  6 +-
 3 files changed, 41 insertions(+), 34 deletions(-)
 create mode 100644 .changeset/list-tables-post.md

diff --git a/.changeset/list-tables-post.md b/.changeset/list-tables-post.md
new file mode 100644
index 00000000..a6871cea
--- /dev/null
+++ b/.changeset/list-tables-post.md
@@ -0,0 +1,5 @@
+---
+"@proofkit/typegen": patch
+---
+
+Fix list-tables endpoint 431 error by converting from GET to POST
diff --git a/packages/typegen/src/server/app.ts b/packages/typegen/src/server/app.ts
index f50af4c2..3a51450b 100644
--- a/packages/typegen/src/server/app.ts
+++ b/packages/typegen/src/server/app.ts
@@ -432,42 +432,44 @@ export function createApiApp(context: ApiContext) {
         }
       },
     )
-    .get("/list-tables", zValidator("query", z.object({ config: z.string() })), async (c) => {
-      const input = c.req.valid("query");
-      // Parse the JSON-encoded config string
-      let config: z.infer<typeof typegenConfigSingle>;
-      try {
-        config = typegenConfigSingle.parse(JSON.parse(input.config));
-      } catch (_err) {
-        return c.json({ error: "Invalid config format" }, 400);
-      }
-      if (config.type !== "fmodata") {
-        return c.json({ error: "Invalid config type" }, 400);
-      }
-      try {
-        const result = createOdataClientFromConfig(config);
-        if ("error" in result) {
+    .post(
+      "/list-tables",
+      zValidator("json", z.object({ config: typegenConfigSingleRequestForValidation })),
+      async (c) => {
+        const rawInput = c.req.valid("json");
+        const configWithType =
+          "type" in rawInput.config && rawInput.config.type
+            ? rawInput.config
+            : { ...(rawInput.config as Record<string, unknown>), type: "fmdapi" as const };
+        const config = typegenConfigSingle.parse(configWithType);
+        if (config.type !== "fmodata") {
+          return c.json({ error: "Invalid config type" }, 400);
+        }
+        try {
+          const result = createOdataClientFromConfig(config);
+          if ("error" in result) {
+            return c.json(
+              {
+                error: result.error,
+                kind: result.kind,
+                suspectedField: result.suspectedField,
+              },
+              result.statusCode as ContentfulStatusCode,
+            );
+          }
+          const { db } = result;
+          const tableNames = await db.listTableNames();
+          return c.json({ tables: tableNames });
+        } catch (err) {
           return c.json(
             {
-              error: result.error,
-              kind: result.kind,
-              suspectedField: result.suspectedField,
+              error: err instanceof Error ? err.message : "Failed to list tables",
             },
-            result.statusCode as ContentfulStatusCode,
+            500,
           );
         }
-        const { db } = result;
-        const tableNames = await db.listTableNames();
-        return c.json({ tables: tableNames });
-      } catch (err) {
-        return c.json(
-          {
-            error: err instanceof Error ? err.message : "Failed to list tables",
-          },
-          500,
-        );
-      }
-    })
+      },
+    )
     // POST /api/test-connection
     .post(
       "/test-connection",
diff --git a/packages/typegen/web/src/hooks/useListTables.ts b/packages/typegen/web/src/hooks/useListTables.ts
index d45c6ae8..dc917259 100644
--- a/packages/typegen/web/src/hooks/useListTables.ts
+++ b/packages/typegen/web/src/hooks/useListTables.ts
@@ -24,9 +24,9 @@ export function useListTables(configIndex: number, enabled?: boolean) {
         throw new Error("Config not found or invalid type");
       }
 
-      const res = await client.api["list-tables"].$get({
-        query: {
-          config: JSON.stringify(config),
+      const res = await client.api["list-tables"].$post({
+        json: {
+          config,
         },
       });