diff --git a/artifacts/api-server/src/routes/executive-meetings.ts b/artifacts/api-server/src/routes/executive-meetings.ts
index 7f57586d..99e5ffff 100644
--- a/artifacts/api-server/src/routes/executive-meetings.ts
+++ b/artifacts/api-server/src/routes/executive-meetings.ts
@@ -25,6 +25,7 @@ import {
   executiveMeetingAlertStateTable,
   rolesTable,
   usersTable,
+  EXECUTIVE_MEETING_ROW_COLOR_KEYS,
   type ExecutiveMeetingAttendee,
 } from "@workspace/db";
 import {
@@ -159,18 +160,11 @@ const requireAdminAudit = makeRequireRoles(ADMIN_AUDIT_ROLES);
 // Allowed values for the row-highlight overlay on the daily schedule.
 // Mirrors the ROW_COLOR_OPTIONS palette in the frontend (
 // artifacts/tx-os/src/pages/executive-meetings.tsx). NULL/omitted on the
-// wire = "default" (no tint). Kept as a literal whitelist (not a string
-// max-length check) so an unknown key is rejected with 400 instead of
-// silently persisting a colour the UI cannot render.
-const ROW_COLOR_KEYS = [
-  "red",
-  "amber",
-  "green",
-  "blue",
-  "violet",
-  "gray",
-] as const;
-const rowColorSchema = z.enum(ROW_COLOR_KEYS).nullable();
+// wire = "default" (no tint). The whitelist itself is exported from
+// the schema package (#293) so the API guard, the Drizzle CHECK
+// constraint, and any future caller share one source of truth — change
+// the palette in one place and both layers stay in sync.
+const rowColorSchema = z.enum(EXECUTIVE_MEETING_ROW_COLOR_KEYS).nullable();
 
 const dateSchema = z.string().regex(/^\d{4}-\d{2}-\d{2}$/, "expected YYYY-MM-DD");
 
diff --git a/artifacts/api-server/tests/executive-meetings-row-color.test.mjs b/artifacts/api-server/tests/executive-meetings-row-color.test.mjs
index a0fdb793..9625426a 100644
--- a/artifacts/api-server/tests/executive-meetings-row-color.test.mjs
+++ b/artifacts/api-server/tests/executive-meetings-row-color.test.mjs
@@ -369,6 +369,104 @@ test("PATCH rowColor: the realtime executive_meetings_changed event fires for th
   }
 });
 
+test("DB CHECK constraint rejects off-palette rowColor on raw UPDATE that bypasses the API (#293)", async () => {
+  // The API's Zod whitelist is the primary guard, but #293 adds a
+  // matching CHECK constraint on `executive_meetings.row_color` so
+  // any out-of-band write path (manual psql, future bulk jobs,
+  // restored backups) cannot smuggle an unrenderable colour into the
+  // table either. This test bypasses the route entirely and writes
+  // straight to the DB to prove the constraint is doing its job.
+  const meeting = await createMeeting(
+    "RowColor DB check",
+    "قيد التحقق على مستوى قاعدة البيانات",
+  );
+
+  // Sanity: a NULL (default / no tint) update must still succeed —
+  // the constraint allows NULL to preserve the "no colour" case.
+  await pool.query(
+    `UPDATE executive_meetings SET row_color = NULL WHERE id = $1`,
+    [meeting.id],
+  );
+
+  // Each of the six palette keys must round-trip cleanly so we know
+  // the literal-list inside the CHECK matches the API whitelist.
+  for (const good of ["red", "amber", "green", "blue", "violet", "gray"]) {
+    await pool.query(
+      `UPDATE executive_meetings SET row_color = $1 WHERE id = $2`,
+      [good, meeting.id],
+    );
+  }
+
+  // Anything outside the palette must be rejected with PG's
+  // check_violation (SQLSTATE 23514) and must NOT change the stored
+  // colour. Cover a few realistic mistakes a future bulk-import
+  // script might introduce: an unsupported key, a casing slip, an
+  // empty string, and the magic string "default" the UI uses for
+  // the "no tint" radio option (which on the wire is supposed to be
+  // null, not the literal "default").
+  for (const bad of ["fuchsia", "RED", "", "default", "red ", "blue;--"]) {
+    await assert.rejects(
+      pool.query(
+        `UPDATE executive_meetings SET row_color = $1 WHERE id = $2`,
+        [bad, meeting.id],
+      ),
+      (err) => {
+        assert.equal(
+          err.code,
+          "23514",
+          `expected PG check_violation for "${bad}", got ${err.code}: ${err.message}`,
+        );
+        assert.match(
+          err.constraint ?? "",
+          /executive_meetings_row_color_palette_check/,
+          `error should reference the row-colour palette CHECK constraint, got "${err.constraint}"`,
+        );
+        return true;
+      },
+    );
+  }
+
+  // Last good colour was "gray" — confirm the rejected updates did
+  // not silently mutate the row.
+  const { rows } = await pool.query(
+    `SELECT row_color FROM executive_meetings WHERE id = $1`,
+    [meeting.id],
+  );
+  assert.equal(
+    rows[0]?.row_color,
+    "gray",
+    "rejected updates must leave the previous colour intact",
+  );
+
+  // Belt-and-braces: also exercise INSERT, since a future bulk-import
+  // job is more likely to create rows than to UPDATE in place. The
+  // constraint must reject the off-palette value at row creation too,
+  // not only on subsequent updates.
+  await assert.rejects(
+    pool.query(
+      `INSERT INTO executive_meetings (title_ar, title_en, meeting_date, daily_number, row_color)
+       VALUES ($1, $2, $3, $4, $5)`,
+      [
+        "INSERT-check probe",
+        "INSERT-check probe",
+        today,
+        // High daily_number to dodge the unique (date, daily_number)
+        // index against meetings created earlier in this file.
+        99000 + Math.floor(Math.random() * 999),
+        "fuchsia",
+      ],
+    ),
+    (err) => {
+      assert.equal(err.code, "23514");
+      assert.match(
+        err.constraint ?? "",
+        /executive_meetings_row_color_palette_check/,
+      );
+      return true;
+    },
+  );
+});
+
 test("PATCH rowColor: each successful change writes an audit row attributed to the acting user", async () => {
   const meeting = await createMeeting("RowColor audit", "سجل لون الصف");
 
diff --git a/lib/db/src/schema/executive-meetings.ts b/lib/db/src/schema/executive-meetings.ts
index 5f309b1b..0f670b5e 100644
--- a/lib/db/src/schema/executive-meetings.ts
+++ b/lib/db/src/schema/executive-meetings.ts
@@ -11,9 +11,28 @@ import {
   boolean,
   index,
   uniqueIndex,
+  check,
 } from "drizzle-orm/pg-core";
+import { sql } from "drizzle-orm";
 import { usersTable } from "./users";
 
+// Single source of truth for the row-highlight palette used by the
+// daily schedule overlay (#288). Imported by the API route's Zod
+// whitelist AND pinned at the database layer via the CHECK constraint
+// below (#293), so the same invariant survives any out-of-band write
+// path (manual SQL, future bulk jobs, restored backups). NULL means
+// "no tint" / default; any other value must be one of these keys.
+export const EXECUTIVE_MEETING_ROW_COLOR_KEYS = [
+  "red",
+  "amber",
+  "green",
+  "blue",
+  "violet",
+  "gray",
+] as const;
+export type ExecutiveMeetingRowColor =
+  (typeof EXECUTIVE_MEETING_ROW_COLOR_KEYS)[number];
+
 export const executiveMeetingsTable = pgTable(
   "executive_meetings",
   {
@@ -72,6 +91,25 @@ export const executiveMeetingsTable = pgTable(
       t.meetingDate,
       t.dailyNumber,
     ),
+    // Defense-in-depth (#293): mirror the API-side ROW_COLOR_KEYS
+    // whitelist at the DB layer so any out-of-band write path
+    // (manual SQL, future bulk jobs, restored backups) cannot smuggle
+    // an unrenderable colour past the Zod guard. NULL is the "no tint"
+    // sentinel, the six keys are the supported palette. Any other
+    // value raises a check_violation (PG SQLSTATE 23514) that the
+    // caller must explicitly handle.
+    // Literal-SQL form: Postgres CHECK constraint definitions are
+    // parsed as DDL and reject parameter placeholders ($1, $2, …),
+    // so the palette keys are inlined as quoted literals via
+    // `sql.raw`. This is safe because the keys come from a hardcoded
+    // compile-time constant of single-word identifiers (no user
+    // input ever reaches this string).
+    rowColorPaletteCheck: check(
+      "executive_meetings_row_color_palette_check",
+      sql`${t.rowColor} IS NULL OR ${t.rowColor} IN (${sql.raw(
+        EXECUTIVE_MEETING_ROW_COLOR_KEYS.map((k) => `'${k}'`).join(", "),
+      )})`,
+    ),
   }),
 );