diff --git a/apps/api/src/routes/daily-notes.ts b/apps/api/src/routes/daily-notes.ts
new file mode 100644
index 0000000..e99d220
--- /dev/null
+++ b/apps/api/src/routes/daily-notes.ts
@@ -0,0 +1,128 @@
+import { Hono } from "hono";
+import { db, dailyNotes } from "@project-e/db";
+import { and, desc, eq } from "drizzle-orm";
+import { requireAuth, resolveActiveDomain, AuthError } from "../middleware/auth";
+import { recordActivity } from "../middleware/activity";
+import { z } from "zod";
+
+export const dailyNoteRoutes = new Hono();
+
+const createDailyNoteSchema = z.object({
+  date: z.string().regex(/^\d{4}-\d{2}-\d{2}$/, "Date must be YYYY-MM-DD"),
+  content: z.string().optional().nullable(),
+  domain: z.string().min(1, "Domain is required"),
+  mood: z.number().int().min(1).max(10).optional().nullable(),
+  energy: z.number().int().min(1).max(10).optional().nullable(),
+  customFields: z.record(z.string(), z.unknown()).optional(),
+});
+
+const updateDailyNoteSchema = z.object({
+  content: z.string().optional().nullable(),
+  mood: z.number().int().min(1).max(10).optional().nullable(),
+  energy: z.number().int().min(1).max(10).optional().nullable(),
+  customFields: z.record(z.string(), z.unknown()).optional(),
+});
+
+// GET /api/daily-notes?date=YYYY-MM-DD — Read
+dailyNoteRoutes.get("/", async (c) => {
+  try {
+    const user = await requireAuth(c);
+    const dateStr = c.req.query("date");
+    let domainId = c.req.query("domain") || undefined;
+    if (!domainId) {
+      const active = await resolveActiveDomain(user);
+      domainId = active.id;
+    }
+
+    if (dateStr) {
+      const startOfDay = new Date(dateStr + "T00:00:00.000Z");
+      const endOfDay = new Date(dateStr + "T23:59:59.999Z");
+      const [note] = await db.select()
+        .from(dailyNotes)
+        .where(and(
+          eq(dailyNotes.domainId, domainId),
+          eq(dailyNotes.date, startOfDay),
+        ))
+        .limit(1);
+      return c.json(note || null);
+    }
+
+    // List all daily notes for domain
+    const items = await db.select()
+      .from(dailyNotes)
+      .where(eq(dailyNotes.domainId, domainId))
+      .orderBy(desc(dailyNotes.date));
+    return c.json({ items, totalItems: items.length });
+  } catch (error) {
+    if (error instanceof AuthError) return c.json({ error: { code: error.code, message: error.message } }, error.status as any);
+    console.error("[daily-notes] GET error:", error);
+    return c.json({ error: { code: "INTERNAL_ERROR", message: "Failed to get daily note" } }, 500);
+  }
+});
+
+// POST /api/daily-notes — Create for a date
+dailyNoteRoutes.post("/", async (c) => {
+  try {
+    const user = await requireAuth(c);
+    const body = await c.req.json();
+    const data = createDailyNoteSchema.parse({
+      ...body,
+      domain: body.domain || (await resolveActiveDomain(user)).id,
+    });
+
+    const [note] = await db.insert(dailyNotes).values({
+      date: new Date(data.date + "T00:00:00.000Z"),
+      content: data.content ?? null,
+      domainId: data.domain,
+      mood: data.mood ?? null,
+      energy: data.energy ?? null,
+      customFields: data.customFields ?? {},
+    }).returning();
+
+    await recordActivity({
+      actor: user.name, action: "created", entityType: "daily_note", entityId: note.id,
+      changes: { date: data.date }, workspaceId: data.domain,
+    });
+
+    return c.json(note, 201);
+  } catch (error) {
+    if (error instanceof AuthError) return c.json({ error: { code: error.code, message: error.message } }, error.status as any);
+    if (error instanceof z.ZodError) return c.json({ error: { code: "VALIDATION_ERROR", message: "Invalid input", details: error.issues } }, 400);
+    console.error("[daily-notes] POST error:", error);
+    return c.json({ error: { code: "INTERNAL_ERROR", message: "Failed to create daily note" } }, 500);
+  }
+});
+
+// PATCH /api/daily-notes/:id — Update content
+dailyNoteRoutes.patch("/:id", async (c) => {
+  try {
+    const user = await requireAuth(c);
+    const id = c.req.param("id");
+    const body = await c.req.json();
+    const data = updateDailyNoteSchema.parse(body);
+
+    const [existing] = await db.select().from(dailyNotes).where(eq(dailyNotes.id, id)).limit(1);
+    if (!existing) return c.json({ error: { code: "NOT_FOUND", message: "Daily note not found" } }, 404);
+
+    const updateValues: Record<string, unknown> = {};
+    if (data.content !== undefined) updateValues.content = data.content;
+    if (data.mood !== undefined) updateValues.mood = data.mood;
+    if (data.energy !== undefined) updateValues.energy = data.energy;
+    if (data.customFields !== undefined) updateValues.customFields = data.customFields;
+    updateValues.updatedAt = new Date();
+
+    const [updated] = await db.update(dailyNotes).set(updateValues).where(eq(dailyNotes.id, id)).returning();
+
+    await recordActivity({
+      actor: user.name, action: "updated", entityType: "daily_note", entityId: id,
+      changes: { date: existing.date.toISOString() }, workspaceId: existing.domainId,
+    });
+
+    return c.json(updated);
+  } catch (error) {
+    if (error instanceof AuthError) return c.json({ error: { code: error.code, message: error.message } }, error.status as any);
+    if (error instanceof z.ZodError) return c.json({ error: { code: "VALIDATION_ERROR", message: "Invalid input", details: error.issues } }, 400);
+    console.error("[daily-notes] PATCH error:", error);
+    return c.json({ error: { code: "INTERNAL_ERROR", message: "Failed to update daily note" } }, 500);
+  }
+});