diff --git a/src/app/api/insights/feedback/route.ts b/src/app/api/insights/feedback/route.ts
new file mode 100644
index 000000000..9da640866
--- /dev/null
+++ b/src/app/api/insights/feedback/route.ts
@@ -0,0 +1,103 @@
+import type { NextRequest } from "next/server";
+
+import { apiHandler, requireAuth } from "@/lib/api-handler";
+import { apiError, apiSuccess, getClientIp, safeJson } from "@/lib/api-response";
+import { auditLog } from "@/lib/auth/audit";
+import { prisma } from "@/lib/db";
+import { Prisma } from "@/generated/prisma/client";
+import { resolveFeedbackAttribution } from "@/lib/ai/feedback-attribution";
+import { withIdempotency } from "@/lib/idempotency";
+import { annotate } from "@/lib/logging/context";
+import { recommendationFeedbackRequestSchema } from "@/lib/validations/recommendation-feedback";
+
+/**
+ * v1.4.16 phase B5e — POST /api/insights/feedback.
+ *
+ * Per-recommendation thumbs-up / thumbs-down. The body contains the
+ * rec id + snapshot text + severity + metric-source attributes the
+ * client just rendered. Server-side fills providerType + promptVersion
+ * via `resolveFeedbackAttribution()` so the client cannot tamper with
+ * the slice the daily aggregator computes.
+ *
+ * The endpoint is idempotent via `withIdempotency()` — a retry with
+ * the same `Idempotency-Key` for the same `(userId, method, path)`
+ * replays the cached response with `X-Idempotent-Replay: true`.
+ *
+ * 201 on insert; 409 on the `(userId, recommendationId,
+ * recommendationText)` unique violation (the user already rated this
+ * exact rec text). 422 on a validation failure.
+ */
+async function handlePost(request: NextRequest) {
+  const { user } = await requireAuth();
+
+  const { data: rawBody, error } = await safeJson<unknown>(request);
+  if (error) return error;
+
+  const parsed = recommendationFeedbackRequestSchema.safeParse(rawBody);
+  if (!parsed.success) {
+    annotate({
+      action: { name: "insights.recommendation.feedback" },
+      meta: { outcome: "validation_failed" },
+    });
+    return apiError("Invalid feedback payload", 422);
+  }
+  const body = parsed.data;
+
+  const attribution = await resolveFeedbackAttribution(user.id);
+
+  try {
+    const created = await prisma.recommendationFeedback.create({
+      data: {
+        userId: user.id,
+        recommendationId: body.recommendationId,
+        recommendationText: body.recommendationText,
+        recommendationSeverity: body.recommendationSeverity,
+        metricSourceType: body.metricSourceType,
+        metricSourceTimeRange: body.metricSourceTimeRange,
+        helpful: body.helpful,
+        providerType: attribution.providerType,
+        promptVersion: attribution.promptVersion,
+      },
+      select: { id: true, createdAt: true },
+    });
+
+    await auditLog("insights.recommendation.feedback", {
+      userId: user.id,
+      ipAddress: getClientIp(request),
+      details: {
+        feedbackId: created.id,
+        recommendationId: body.recommendationId,
+        severity: body.recommendationSeverity,
+        helpful: body.helpful,
+        providerType: attribution.providerType,
+        promptVersion: attribution.promptVersion,
+      },
+    });
+
+    annotate({
+      action: { name: "insights.recommendation.feedback" },
+      meta: {
+        outcome: "created",
+        severity: body.recommendationSeverity,
+        helpful: body.helpful,
+        providerType: attribution.providerType,
+      },
+    });
+
+    return apiSuccess({ id: created.id, createdAt: created.createdAt }, 201);
+  } catch (err) {
+    if (
+      err instanceof Prisma.PrismaClientKnownRequestError &&
+      err.code === "P2002"
+    ) {
+      annotate({
+        action: { name: "insights.recommendation.feedback" },
+        meta: { outcome: "already_rated" },
+      });
+      return apiError("already_rated", 409);
+    }
+    throw err;
+  }
+}
+
+export const POST = apiHandler(withIdempotency(handlePost));
diff --git a/src/lib/ai/__tests__/feedback-attribution.test.ts b/src/lib/ai/__tests__/feedback-attribution.test.ts
new file mode 100644
index 000000000..954f0e156
--- /dev/null
+++ b/src/lib/ai/__tests__/feedback-attribution.test.ts
@@ -0,0 +1,48 @@
+import { describe, it, expect } from "vitest";
+import {
+  FEEDBACK_ATTRIBUTION_FALLBACK,
+  pickProviderType,
+} from "../feedback-attribution";
+import { PROMPT_VERSION } from "@/lib/ai/prompts/insight-generator";
+
+describe("pickProviderType", () => {
+  it("prefers chainProviderType when present", () => {
+    // chainProviderType captures the runner's chosen entry across the
+    // multi-provider chain (B5b). When a fallback fires, the working
+    // provider differs from the user's primary — the feedback row must
+    // reflect the working provider, not the configured one.
+    const got = pickProviderType({
+      chainProviderType: "openai",
+      providerType: "codex",
+    });
+    expect(got).toBe("openai");
+  });
+
+  it("falls back to providerType when chainProviderType is missing", () => {
+    const got = pickProviderType({ providerType: "codex" });
+    expect(got).toBe("codex");
+  });
+
+  it("falls back to 'unknown' when neither field is present", () => {
+    const got = pickProviderType({});
+    expect(got).toBe("unknown");
+  });
+
+  it("ignores non-string values", () => {
+    const got = pickProviderType({
+      chainProviderType: 123 as unknown as string,
+      providerType: { name: "evil" } as unknown as string,
+    });
+    expect(got).toBe("unknown");
+  });
+});
+
+describe("FEEDBACK_ATTRIBUTION_FALLBACK", () => {
+  it("uses 'unknown' for the providerType so the aggregator groups separately", () => {
+    expect(FEEDBACK_ATTRIBUTION_FALLBACK.providerType).toBe("unknown");
+  });
+
+  it("snapshots the current PROMPT_VERSION so the row is persistable", () => {
+    expect(FEEDBACK_ATTRIBUTION_FALLBACK.promptVersion).toBe(PROMPT_VERSION);
+  });
+});
diff --git a/src/lib/ai/feedback-attribution.ts b/src/lib/ai/feedback-attribution.ts
new file mode 100644
index 000000000..74c856c57
--- /dev/null
+++ b/src/lib/ai/feedback-attribution.ts
@@ -0,0 +1,86 @@
+/**
+ * v1.4.16 phase B5e — server-side resolver for the provider/prompt
+ * attribution that gets stamped on every `RecommendationFeedback` row.
+ *
+ * The client cannot supply these fields — that would let any user
+ * poison the daily aggregator's slice (`(severity x provider x prompt)
+ * helpful-rate`) by claiming a thumbs-down was attributed to a rival
+ * provider. So the API endpoint reads the user's most recent
+ * `insights.generate` audit row, pulls `chainProviderType` (or its
+ * legacy fallback `providerType`) plus the current `PROMPT_VERSION`
+ * constant, and stamps those on the row.
+ *
+ * If no audit row exists yet (the user is rating a per-status insight
+ * that pre-dates the comprehensive generate flow), we fall back to
+ * "unknown" + the current PROMPT_VERSION so the row is still
+ * persistable and the aggregator can group "unknown" separately.
+ */
+import { prisma } from "@/lib/db";
+import { PROMPT_VERSION } from "@/lib/ai/prompts/insight-generator";
+
+export interface FeedbackAttribution {
+  providerType: string;
+  promptVersion: string;
+}
+
+/** Default attribution when no `insights.generate` row exists yet. */
+export const FEEDBACK_ATTRIBUTION_FALLBACK: Readonly<FeedbackAttribution> = {
+  providerType: "unknown",
+  promptVersion: PROMPT_VERSION,
+};
+
+interface AuditDetailsShape {
+  providerType?: unknown;
+  chainProviderType?: unknown;
+}
+
+function parseAuditDetails(raw: string | null): AuditDetailsShape {
+  if (!raw) return {};
+  try {
+    const parsed = JSON.parse(raw);
+    if (parsed && typeof parsed === "object") return parsed as AuditDetailsShape;
+  } catch {
+    // Treat unparseable details as absent — the fallback applies.
+  }
+  return {};
+}
+
+/**
+ * Pure helper exported for unit tests so we can pin the priority order
+ * (chainProviderType > providerType > "unknown") without hitting the
+ * DB. The current PROMPT_VERSION constant is always returned because
+ * the generator itself doesn't yet stash a per-payload prompt version
+ * (research §3.B notes this is a v1.4.17 ratchet item; reading the
+ * constant snapshots whatever's deployed when the rating fires).
+ */
+export function pickProviderType(details: AuditDetailsShape): string {
+  if (typeof details.chainProviderType === "string") {
+    return details.chainProviderType;
+  }
+  if (typeof details.providerType === "string") return details.providerType;
+  return FEEDBACK_ATTRIBUTION_FALLBACK.providerType;
+}
+
+/**
+ * Resolve the (providerType, promptVersion) tuple to stamp on a
+ * `RecommendationFeedback` row. Reads the latest `insights.generate`
+ * audit row for the user. Falls back to the safe defaults when no
+ * audit row exists.
+ */
+export async function resolveFeedbackAttribution(
+  userId: string,
+): Promise<FeedbackAttribution> {
+  const latest = await prisma.auditLog.findFirst({
+    where: { userId, action: "insights.generate" },
+    orderBy: { createdAt: "desc" },
+    select: { details: true },
+  });
+
+  if (!latest) return { ...FEEDBACK_ATTRIBUTION_FALLBACK };
+
+  const details = parseAuditDetails(latest.details);
+  return {
+    providerType: pickProviderType(details),
+    promptVersion: PROMPT_VERSION,
+  };
+}
diff --git a/src/lib/validations/__tests__/recommendation-feedback.test.ts b/src/lib/validations/__tests__/recommendation-feedback.test.ts
new file mode 100644
index 000000000..ba297d0e7
--- /dev/null
+++ b/src/lib/validations/__tests__/recommendation-feedback.test.ts
@@ -0,0 +1,72 @@
+import { describe, it, expect } from "vitest";
+import { recommendationFeedbackRequestSchema } from "../recommendation-feedback";
+
+describe("recommendationFeedbackRequestSchema", () => {
+  const baseValid = {
+    recommendationId: "rec-1",
+    recommendationText: "Discuss home BP log with your physician.",
+    recommendationSeverity: "important" as const,
+    metricSourceType: "bloodPressure",
+    metricSourceTimeRange: "last7days" as const,
+    helpful: true,
+  };
+
+  it("accepts a valid payload", () => {
+    const parsed = recommendationFeedbackRequestSchema.safeParse(baseValid);
+    expect(parsed.success).toBe(true);
+  });
+
+  it("rejects an unknown severity (defence against poisoning the aggregator)", () => {
+    const parsed = recommendationFeedbackRequestSchema.safeParse({
+      ...baseValid,
+      recommendationSeverity: "wat",
+    });
+    expect(parsed.success).toBe(false);
+  });
+
+  it("rejects an unknown time-range value", () => {
+    const parsed = recommendationFeedbackRequestSchema.safeParse({
+      ...baseValid,
+      metricSourceTimeRange: "lastFortnight",
+    });
+    expect(parsed.success).toBe(false);
+  });
+
+  it("rejects an empty recommendation id", () => {
+    const parsed = recommendationFeedbackRequestSchema.safeParse({
+      ...baseValid,
+      recommendationId: "",
+    });
+    expect(parsed.success).toBe(false);
+  });
+
+  it("rejects an empty recommendation text", () => {
+    const parsed = recommendationFeedbackRequestSchema.safeParse({
+      ...baseValid,
+      recommendationText: "",
+    });
+    expect(parsed.success).toBe(false);
+  });
+
+  it("rejects a non-boolean helpful field (catches stringified-boolean clients)", () => {
+    const parsed = recommendationFeedbackRequestSchema.safeParse({
+      ...baseValid,
+      helpful: "true",
+    });
+    expect(parsed.success).toBe(false);
+  });
+
+  it("rejects extra fields when stripping isn't desired (helpful is the only thumbs verb)", () => {
+    // Zod default behaviour: passthrough is OFF; unknown keys are
+    // dropped. We don't use .strict() so a future field can be added
+    // additively, but the parsed value must not carry the extra field.
+    const parsed = recommendationFeedbackRequestSchema.safeParse({
+      ...baseValid,
+      providerType: "codex",
+    });
+    expect(parsed.success).toBe(true);
+    if (parsed.success) {
+      expect("providerType" in parsed.data).toBe(false);
+    }
+  });
+});
diff --git a/src/lib/validations/recommendation-feedback.ts b/src/lib/validations/recommendation-feedback.ts
new file mode 100644
index 000000000..d4728fd9e
--- /dev/null
+++ b/src/lib/validations/recommendation-feedback.ts
@@ -0,0 +1,53 @@
+import { z } from "zod/v4";
+
+/**
+ * v1.4.16 phase B5e — request body for `POST /api/insights/feedback`.
+ *
+ * Mirrors the `RecommendationFeedback` Prisma model fields the client
+ * is allowed to specify. `providerType` and `promptVersion` are NOT
+ * part of the request shape — the server fills them from the user's
+ * most recent cached payload + the current PROMPT_VERSION constant
+ * so the client can't tamper with the attribution that the daily
+ * aggregator slices on for the admin AI quality dashboard.
+ *
+ * Severity + dataWindow are constrained to the same vocabulary as the
+ * AI schema (`aiRecommendationSchema` / `aiRecommendationRationaleSchema`)
+ * so a bogus rating attempt with `severity = "wat"` is rejected at the
+ * edge instead of poisoning the aggregator.
+ */
+export const recommendationFeedbackSeverity = z.enum([
+  "info",
+  "suggestion",
+  "important",
+  "urgent",
+]);
+
+export const recommendationFeedbackTimeRange = z.enum([
+  "last7days",
+  "last30days",
+  "last90days",
+  "allTime",
+]);
+
+export const recommendationFeedbackRequestSchema = z.object({
+  /**
+   * Stable per-payload rec id. Dedup happens on
+   * (userId, recommendationId, recommendationText).
+   */
+  recommendationId: z.string().min(1).max(200),
+  /**
+   * Snapshot of the rec text at submission time. Dedup partner so a
+   * regeneration that rewrites the same id with new text counts as a
+   * different row — that's intentional, the aggregator wants per-text
+   * signal not per-id signal.
+   */
+  recommendationText: z.string().min(1).max(2000),
+  recommendationSeverity: recommendationFeedbackSeverity,
+  metricSourceType: z.string().min(1).max(80),
+  metricSourceTimeRange: recommendationFeedbackTimeRange,
+  helpful: z.boolean(),
+});
+
+export type RecommendationFeedbackRequest = z.infer<
+  typeof recommendationFeedbackRequestSchema
+>;
diff --git a/tests/integration/insights-feedback.test.ts b/tests/integration/insights-feedback.test.ts
new file mode 100644
index 000000000..3d4cef0a1
--- /dev/null
+++ b/tests/integration/insights-feedback.test.ts
@@ -0,0 +1,229 @@
+/**
+ * v1.4.16 phase B5e — integration coverage for POST /api/insights/feedback.
+ *
+ * Three scenarios pinned end-to-end against the postgres testcontainer:
+ *   1. POST a valid payload → 201, row persisted with server-filled
+ *      providerType (from the latest insights.generate audit row) +
+ *      promptVersion (from the PROMPT_VERSION constant). Audit log
+ *      entry written with action `insights.recommendation.feedback`.
+ *   2. Re-POST the same (recId, recText) → 409, no second row written.
+ *   3. Validation failure (bad severity) → 422, no row written.
+ */
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+process.env.ENCRYPTION_KEY ??=
+  "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+
+import { cookieJar, headerJar } from "./mock-next-headers";
+import { getPrismaClient, truncateAllTables } from "./setup";
+import { PROMPT_VERSION } from "@/lib/ai/prompts/insight-generator";
+
+vi.mock("next/headers", async () => {
+  const { cookieJar, headerJar } = await import("./mock-next-headers");
+  return {
+    headers: vi.fn(async () => ({
+      get: (name: string) => headerJar.get(name.toLowerCase()) ?? null,
+    })),
+    cookies: vi.fn(async () => ({
+      get: (name: string) => {
+        const value = cookieJar.get(name);
+        return value ? { name, value } : undefined;
+      },
+      set: (name: string, value: string) => {
+        cookieJar.set(name, value);
+      },
+      delete: (name: string) => {
+        cookieJar.delete(name);
+      },
+    })),
+  };
+});
+
+vi.mock("@/lib/db-compat", () => ({
+  ensureDbCompatibility: vi.fn().mockResolvedValue(undefined),
+}));
+
+beforeEach(async () => {
+  await truncateAllTables(getPrismaClient());
+  cookieJar.clear();
+  headerJar.clear();
+});
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+async function seedUserWithAuditedGeneration(): Promise<{
+  userId: string;
+}> {
+  const prisma = getPrismaClient();
+  const user = await prisma.user.create({
+    data: {
+      username: "feedback-user",
+      email: "feedback@example.test",
+      role: "USER",
+    },
+  });
+  const session = await prisma.session.create({
+    data: {
+      userId: user.id,
+      expiresAt: new Date(Date.now() + 60_000),
+    },
+  });
+  cookieJar.set("healthlog_session", session.id);
+
+  // Seed a recent insights.generate audit row so the feedback endpoint
+  // can pull `chainProviderType` from it for provider attribution.
+  await prisma.auditLog.create({
+    data: {
+      userId: user.id,
+      action: "insights.generate",
+      details: JSON.stringify({
+        privacyMode: "aggregated",
+        providerType: "openai",
+        chainProviderType: "codex",
+        fallbackHopCount: 0,
+        tokensUsed: 1234,
+        model: "gpt-4o-mini",
+      }),
+    },
+  });
+
+  return { userId: user.id };
+}
+
+const baseBody = {
+  recommendationId: "rec-1",
+  recommendationText: "Discuss home BP log with your physician.",
+  recommendationSeverity: "important",
+  metricSourceType: "bloodPressure",
+  metricSourceTimeRange: "last7days",
+  helpful: true,
+};
+
+interface FeedbackEnvelope {
+  data: { id: string; createdAt: string } | null;
+  error?: string | null;
+}
+
+describe("POST /api/insights/feedback — integration", () => {
+  it("persists a valid feedback row with server-filled provider attribution", async () => {
+    const { userId } = await seedUserWithAuditedGeneration();
+    const { POST } = await import("@/app/api/insights/feedback/route");
+
+    const res = await (POST as (req: Request) => Promise<Response>)(
+      new Request("http://localhost/api/insights/feedback", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify(baseBody),
+      }),
+    );
+    expect(res.status).toBe(201);
+    const env = (await res.json()) as FeedbackEnvelope;
+    expect(env.data?.id).toBeTruthy();
+
+    const prisma = getPrismaClient();
+    const rows = await prisma.recommendationFeedback.findMany({
+      where: { userId },
+    });
+    expect(rows).toHaveLength(1);
+    const row = rows[0];
+    expect(row.recommendationId).toBe(baseBody.recommendationId);
+    expect(row.recommendationText).toBe(baseBody.recommendationText);
+    expect(row.recommendationSeverity).toBe(baseBody.recommendationSeverity);
+    expect(row.metricSourceType).toBe(baseBody.metricSourceType);
+    expect(row.metricSourceTimeRange).toBe(baseBody.metricSourceTimeRange);
+    expect(row.helpful).toBe(true);
+    // Server fills providerType + promptVersion — the body never
+    // supplied them.
+    expect(row.providerType).toBe("codex");
+    expect(row.promptVersion).toBe(PROMPT_VERSION);
+
+    // Audit row was written with the right action.
+    const audit = await prisma.auditLog.findFirst({
+      where: { userId, action: "insights.recommendation.feedback" },
+    });
+    expect(audit).not.toBeNull();
+  });
+
+  it("rejects a duplicate (recId, recText) with 409", async () => {
+    const { userId } = await seedUserWithAuditedGeneration();
+    const { POST } = await import("@/app/api/insights/feedback/route");
+
+    const first = await (POST as (req: Request) => Promise<Response>)(
+      new Request("http://localhost/api/insights/feedback", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify(baseBody),
+      }),
+    );
+    expect(first.status).toBe(201);
+
+    const second = await (POST as (req: Request) => Promise<Response>)(
+      new Request("http://localhost/api/insights/feedback", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify(baseBody),
+      }),
+    );
+    expect(second.status).toBe(409);
+
+    const prisma = getPrismaClient();
+    expect(
+      await prisma.recommendationFeedback.count({ where: { userId } }),
+    ).toBe(1);
+  });
+
+  it("rejects a bad severity with 422 and writes no row", async () => {
+    const { userId } = await seedUserWithAuditedGeneration();
+    const { POST } = await import("@/app/api/insights/feedback/route");
+
+    const res = await (POST as (req: Request) => Promise<Response>)(
+      new Request("http://localhost/api/insights/feedback", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify({ ...baseBody, recommendationSeverity: "wat" }),
+      }),
+    );
+    expect(res.status).toBe(422);
+
+    const prisma = getPrismaClient();
+    expect(
+      await prisma.recommendationFeedback.count({ where: { userId } }),
+    ).toBe(0);
+  });
+
+  it("falls back to providerType=unknown when no insights.generate audit row exists", async () => {
+    const prisma = getPrismaClient();
+    const user = await prisma.user.create({
+      data: {
+        username: "fallback-user",
+        email: "fallback-feedback@example.test",
+        role: "USER",
+      },
+    });
+    const session = await prisma.session.create({
+      data: {
+        userId: user.id,
+        expiresAt: new Date(Date.now() + 60_000),
+      },
+    });
+    cookieJar.set("healthlog_session", session.id);
+
+    const { POST } = await import("@/app/api/insights/feedback/route");
+    const res = await (POST as (req: Request) => Promise<Response>)(
+      new Request("http://localhost/api/insights/feedback", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify(baseBody),
+      }),
+    );
+    expect(res.status).toBe(201);
+
+    const row = await prisma.recommendationFeedback.findFirst({
+      where: { userId: user.id },
+    });
+    expect(row?.providerType).toBe("unknown");
+    expect(row?.promptVersion).toBe(PROMPT_VERSION);
+  });
+});