diff --git a/__tests__/artifact-comments-route.test.ts b/__tests__/artifact-comments-route.test.ts
index ce2e06a7..e00a5e56 100644
--- a/__tests__/artifact-comments-route.test.ts
+++ b/__tests__/artifact-comments-route.test.ts
@@ -16,8 +16,8 @@ describe("/api/artifacts/[id]/comments", () => {
     process.env.FORAGENTS_API_KEYS_JSON = JSON.stringify({
       testkey: { agent_id: "agt_test", handle: "@test@local", display_name: "Test" },
     });
-    const rl = await import("@/lib/server/rateLimit");
-    rl._resetRateLimitForTests();
+    const rl = await import("@/lib/requestLimits");
+    rl.__resetRateLimitsForTests();
 
     // Ensure file-backed store is clean per test.
     const { promises: fs } = await import("fs");
@@ -80,6 +80,24 @@ describe("/api/artifacts/[id]/comments", () => {
     expect(typeof json.comment.created_at).toBe("string");
   });
 
+  test("POST returns 413 when request body is too large", async () => {
+    const { POST } = await loadRoute();
+
+    const huge = "a".repeat(30_000);
+    const req = new NextRequest("http://localhost/api/artifacts/art_1/comments", {
+      method: "POST",
+      body: huge,
+      headers: {
+        "Content-Type": "text/markdown; charset=utf-8",
+        Authorization: "Bearer testkey",
+        "x-forwarded-for": "203.0.113.10",
+      },
+    });
+
+    const res = await POST(req, { params: Promise.resolve({ id: "art_1" }) });
+    expect(res.status).toBe(413);
+  });
+
   test("GET returns list shape", async () => {
     const { GET } = await loadRoute();
     const req = new NextRequest("http://localhost/api/artifacts/art_1/comments?limit=2&order=asc");
diff --git a/__tests__/artifact-ratings-route.test.ts b/__tests__/artifact-ratings-route.test.ts
index c5169224..8e67774f 100644
--- a/__tests__/artifact-ratings-route.test.ts
+++ b/__tests__/artifact-ratings-route.test.ts
@@ -20,8 +20,8 @@ describe("/api/artifacts/[id]/ratings", () => {
     process.env.FORAGENTS_API_KEYS_JSON = JSON.stringify({
       testkey: { agent_id: "agt_test", handle: "@test@local", display_name: "Test" },
     });
-    const rl = await import("@/lib/server/rateLimit");
-    rl._resetRateLimitForTests();
+    const rl = await import("@/lib/requestLimits");
+    rl.__resetRateLimitsForTests();
 
     // Ensure file-backed store is clean per test.
     const { promises: fs } = await import("fs");
diff --git a/__tests__/artifacts-feeds.test.ts b/__tests__/artifacts-feeds.test.ts
index 2708eb00..f4f4325c 100644
--- a/__tests__/artifacts-feeds.test.ts
+++ b/__tests__/artifacts-feeds.test.ts
@@ -36,6 +36,7 @@ describe("/feeds/artifacts.json", () => {
     expect(body).toHaveProperty("version");
     expect(body).toHaveProperty("title");
     expect(body).toHaveProperty("items");
+    expect(body.bootstrap_url).toBe("https://foragents.dev/b");
     expect(Array.isArray(body.items)).toBe(true);
   });
 
diff --git a/__tests__/digest-endpoints.test.ts b/__tests__/digest-endpoints.test.ts
index 0b400075..8fd7296a 100644
--- a/__tests__/digest-endpoints.test.ts
+++ b/__tests__/digest-endpoints.test.ts
@@ -37,6 +37,7 @@ describe("/api/digest.{json,md}", () => {
     expect(body).toHaveProperty("counts.new_agents");
     expect(Array.isArray(body.new_artifacts)).toBe(true);
     expect(Array.isArray(body.new_agents)).toBe(true);
+    expect(body.bootstrap_url).toBe("https://foragents.dev/b");
   });
 
   test("GET /api/digest.md returns markdown + cache headers", async () => {
diff --git a/scripts/audit-write-endpoints.baseline.txt b/scripts/audit-write-endpoints.baseline.txt
index 3e0f4395..3fc3dd57 100644
--- a/scripts/audit-write-endpoints.baseline.txt
+++ b/scripts/audit-write-endpoints.baseline.txt
@@ -2,8 +2,6 @@
 # Keep this list shrinking over time.
 
 src/app/api/agents/profile/premium/route.ts
-src/app/api/artifacts/[id]/comments/route.ts
-src/app/api/artifacts/[id]/ratings/route.ts
 src/app/api/artifacts/[id]/remix/route.ts
 src/app/api/collections/[id]/items/[itemId]/route.ts
 src/app/api/collections/[id]/route.ts
diff --git a/src/app/api/artifacts/[id]/comments/route.ts b/src/app/api/artifacts/[id]/comments/route.ts
index 5ff52488..24fa84e3 100644
--- a/src/app/api/artifacts/[id]/comments/route.ts
+++ b/src/app/api/artifacts/[id]/comments/route.ts
@@ -1,6 +1,6 @@
 import { NextRequest, NextResponse } from "next/server";
 import { requireAgentAuth } from "@/lib/server/agent-auth";
-import { checkRateLimit } from "@/lib/server/rateLimit";
+import { checkRateLimit, getClientIp, rateLimitResponse, readJsonWithLimit, readTextWithLimit } from "@/lib/requestLimits";
 import {
   parseMarkdownWithFrontmatter,
   validateCommentFrontmatter,
@@ -14,81 +14,86 @@ import {
 import { logViralEvent } from "@/lib/server/viralMetrics";
 
 const MAX_MD_BYTES = 20_000;
+// Cap the *request* body (slightly above MAX_MD_BYTES to allow JSON wrapper).
+const MAX_BODY_BYTES = 24_000;
 
 async function readMarkdownBody(req: NextRequest): Promise<string> {
   const ct = req.headers.get("content-type") ?? "";
   if (ct.includes("application/json")) {
-    const json = (await req.json().catch(() => null)) as null | { markdown?: unknown };
-    const md = typeof json?.markdown === "string" ? json.markdown : "";
-    return md;
+    const json = await readJsonWithLimit<{ markdown?: unknown }>(req, MAX_BODY_BYTES);
+    return typeof json?.markdown === "string" ? json.markdown : "";
   }
-  return await req.text();
+
+  return await readTextWithLimit(req, MAX_BODY_BYTES);
 }
 
 export async function POST(request: NextRequest, context: { params: Promise<{ id: string }> }) {
-  const { id: artifactId } = await context.params;
-
-  const { agent, errorResponse } = await requireAgentAuth(request);
-  if (errorResponse) return errorResponse;
+  try {
+    const { id: artifactId } = await context.params;
 
-  const rl = checkRateLimit({
-    key: `comments:${agent!.agent_id}`,
-    limit: 20,
-    windowMs: 60 * 60 * 1000,
-  });
-  if (!rl.ok) {
-    return NextResponse.json(
-      { error: "Rate limit exceeded" },
-      { status: 429, headers: { "Retry-After": String(rl.retryAfterSec) } }
-    );
-  }
+    const { agent, errorResponse } = await requireAgentAuth(request);
+    if (errorResponse) return errorResponse;
 
-  const raw = await readMarkdownBody(request);
-  if (!raw || typeof raw !== "string") {
-    return NextResponse.json({ error: "Validation failed", details: ["markdown body is required"] }, { status: 400 });
-  }
+    const ip = getClientIp(request);
+    const rl = checkRateLimit(`artifacts:comments:post:${ip}`, { windowMs: 60_000, max: 20 });
+    if (!rl.ok) return rateLimitResponse(rl.retryAfterSec);
 
-  if (Buffer.byteLength(raw, "utf-8") > MAX_MD_BYTES) {
-    return NextResponse.json(
-      { error: "Validation failed", details: ["body too large"] },
-      { status: 400 }
-    );
-  }
+    const raw = await readMarkdownBody(request);
+    if (!raw || typeof raw !== "string") {
+      return NextResponse.json(
+        { error: "Validation failed", details: ["markdown body is required"] },
+        { status: 400 }
+      );
+    }
 
-  const parsed = parseMarkdownWithFrontmatter<CommentFrontmatter>(raw);
-  const fm = validateCommentFrontmatter(parsed.frontmatter);
+    if (Buffer.byteLength(raw, "utf-8") > MAX_MD_BYTES) {
+      return NextResponse.json({ error: "Request body too large" }, { status: 413 });
+    }
 
-  const details = [...fm.errors];
-  if (fm.artifact_id && fm.artifact_id !== artifactId) details.push("artifact_id mismatch");
-  if (!parsed.body_md || parsed.body_md.length < 1) details.push("body must be >= 1 char");
+    const parsed = parseMarkdownWithFrontmatter<CommentFrontmatter>(raw);
+    const fm = validateCommentFrontmatter(parsed.frontmatter);
 
-  if (details.length) {
-    return NextResponse.json({ error: "Validation failed", details }, { status: 400 });
-  }
+    const details = [...fm.errors];
+    if (fm.artifact_id && fm.artifact_id !== artifactId) details.push("artifact_id mismatch");
+    if (!parsed.body_md || parsed.body_md.length < 1) details.push("body must be >= 1 char");
 
-  if (fm.parent_id) {
-    const exists = await commentExistsOnArtifact(fm.parent_id, artifactId);
-    if (!exists) {
-      return NextResponse.json(
-        { error: "Validation failed", details: ["parent_id not found on artifact"] },
-        { status: 400 }
-      );
+    if (details.length) {
+      return NextResponse.json({ error: "Validation failed", details }, { status: 400 });
     }
-  }
 
-  const comment = await createArtifactComment({
-    artifact_id: artifactId,
-    parent_id: fm.parent_id,
-    kind: fm.kind!,
-    raw_md: parsed.raw_md,
-    body_md: parsed.body_md,
-    body_text: parsed.body_text,
-    author: agent!,
-  });
+    if (fm.parent_id) {
+      const exists = await commentExistsOnArtifact(fm.parent_id, artifactId);
+      if (!exists) {
+        return NextResponse.json(
+          { error: "Validation failed", details: ["parent_id not found on artifact"] },
+          { status: 400 }
+        );
+      }
+    }
 
-  void logViralEvent("comment_created", { artifact_id: artifactId });
+    const comment = await createArtifactComment({
+      artifact_id: artifactId,
+      parent_id: fm.parent_id,
+      kind: fm.kind!,
+      raw_md: parsed.raw_md,
+      body_md: parsed.body_md,
+      body_text: parsed.body_text,
+      author: agent!,
+    });
+
+    void logViralEvent("comment_created", { artifact_id: artifactId });
+
+    return NextResponse.json({ success: true, comment }, { status: 201 });
+  } catch (err) {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const status = typeof (err as any)?.status === "number" ? (err as any).status : 400;
+    if (status === 413) {
+      return NextResponse.json({ error: "Request body too large" }, { status: 413 });
+    }
 
-  return NextResponse.json({ success: true, comment }, { status: 201 });
+    console.error("Artifact comment error:", err);
+    return NextResponse.json({ error: "Invalid request body" }, { status: 400 });
+  }
 }
 
 export async function GET(request: NextRequest, context: { params: Promise<{ id: string }> }) {
diff --git a/src/app/api/artifacts/[id]/ratings/route.ts b/src/app/api/artifacts/[id]/ratings/route.ts
index 9a1a066b..3a3fc489 100644
--- a/src/app/api/artifacts/[id]/ratings/route.ts
+++ b/src/app/api/artifacts/[id]/ratings/route.ts
@@ -1,6 +1,6 @@
 import { NextRequest, NextResponse } from "next/server";
 import { requireAgentAuth } from "@/lib/server/agent-auth";
-import { checkRateLimit } from "@/lib/server/rateLimit";
+import { checkRateLimit, getClientIp, rateLimitResponse, readJsonWithLimit, readTextWithLimit } from "@/lib/requestLimits";
 import {
   parseMarkdownWithFrontmatter,
   validateRatingFrontmatter,
@@ -10,66 +10,71 @@ import { upsertArtifactRating } from "@/lib/server/artifactFeedback";
 import { logViralEvent } from "@/lib/server/viralMetrics";
 
 const MAX_MD_BYTES = 20_000;
+const MAX_BODY_BYTES = 24_000;
 
 async function readMarkdownBody(req: NextRequest): Promise<string> {
   const ct = req.headers.get("content-type") ?? "";
   if (ct.includes("application/json")) {
-    const json = (await req.json().catch(() => null)) as null | { markdown?: unknown };
+    const json = await readJsonWithLimit<{ markdown?: unknown }>(req, MAX_BODY_BYTES);
     return typeof json?.markdown === "string" ? json.markdown : "";
   }
-  return await req.text();
+
+  return await readTextWithLimit(req, MAX_BODY_BYTES);
 }
 
 export async function POST(request: NextRequest, context: { params: Promise<{ id: string }> }) {
-  const { id: artifactId } = await context.params;
+  try {
+    const { id: artifactId } = await context.params;
 
-  const { agent, errorResponse } = await requireAgentAuth(request);
-  if (errorResponse) return errorResponse;
+    const { agent, errorResponse } = await requireAgentAuth(request);
+    if (errorResponse) return errorResponse;
 
-  const rl = checkRateLimit({
-    key: `ratings:${agent!.agent_id}`,
-    limit: 30,
-    windowMs: 60 * 60 * 1000,
-  });
-  if (!rl.ok) {
-    return NextResponse.json(
-      { error: "Rate limit exceeded" },
-      { status: 429, headers: { "Retry-After": String(rl.retryAfterSec) } }
-    );
-  }
+    const ip = getClientIp(request);
+    const rl = checkRateLimit(`artifacts:ratings:post:${ip}`, { windowMs: 60_000, max: 30 });
+    if (!rl.ok) return rateLimitResponse(rl.retryAfterSec);
 
-  const raw = await readMarkdownBody(request);
-  if (!raw || typeof raw !== "string") {
-    return NextResponse.json({ error: "Validation failed", details: ["markdown body is required"] }, { status: 400 });
-  }
+    const raw = await readMarkdownBody(request);
+    if (!raw || typeof raw !== "string") {
+      return NextResponse.json(
+        { error: "Validation failed", details: ["markdown body is required"] },
+        { status: 400 }
+      );
+    }
 
-  if (Buffer.byteLength(raw, "utf-8") > MAX_MD_BYTES) {
-    return NextResponse.json(
-      { error: "Validation failed", details: ["body too large"] },
-      { status: 400 }
-    );
-  }
+    if (Buffer.byteLength(raw, "utf-8") > MAX_MD_BYTES) {
+      return NextResponse.json({ error: "Request body too large" }, { status: 413 });
+    }
 
-  const parsed = parseMarkdownWithFrontmatter<RatingFrontmatter>(raw);
-  const fm = validateRatingFrontmatter(parsed.frontmatter);
+    const parsed = parseMarkdownWithFrontmatter<RatingFrontmatter>(raw);
+    const fm = validateRatingFrontmatter(parsed.frontmatter);
 
-  const details = [...fm.errors];
-  if (fm.artifact_id && fm.artifact_id !== artifactId) details.push("artifact_id mismatch");
+    const details = [...fm.errors];
+    if (fm.artifact_id && fm.artifact_id !== artifactId) details.push("artifact_id mismatch");
 
-  if (details.length) {
-    return NextResponse.json({ error: "Validation failed", details }, { status: 400 });
-  }
+    if (details.length) {
+      return NextResponse.json({ error: "Validation failed", details }, { status: 400 });
+    }
+
+    const { rating, created } = await upsertArtifactRating({
+      artifact_id: artifactId,
+      rater: agent!,
+      score: fm.score!,
+      dims: fm.dims ?? {},
+      raw_md: parsed.raw_md,
+      notes_md: parsed.body_md || null,
+    });
 
-  const { rating, created } = await upsertArtifactRating({
-    artifact_id: artifactId,
-    rater: agent!,
-    score: fm.score!,
-    dims: fm.dims ?? {},
-    raw_md: parsed.raw_md,
-    notes_md: parsed.body_md || null,
-  });
+    void logViralEvent("rating_created_or_updated", { artifact_id: artifactId });
 
-  void logViralEvent("rating_created_or_updated", { artifact_id: artifactId });
+    return NextResponse.json({ success: true, rating }, { status: created ? 201 : 200 });
+  } catch (err) {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const status = typeof (err as any)?.status === "number" ? (err as any).status : 400;
+    if (status === 413) {
+      return NextResponse.json({ error: "Request body too large" }, { status: 413 });
+    }
 
-  return NextResponse.json({ success: true, rating }, { status: created ? 201 : 200 });
+    console.error("Artifact rating error:", err);
+    return NextResponse.json({ error: "Invalid request body" }, { status: 400 });
+  }
 }
diff --git a/src/app/api/digest.json/route.ts b/src/app/api/digest.json/route.ts
index 446e11e7..a97da23b 100644
--- a/src/app/api/digest.json/route.ts
+++ b/src/app/api/digest.json/route.ts
@@ -20,6 +20,13 @@ export async function GET(request: NextRequest) {
 
   const digest = await generateAgentDigest({ since, now });
 
+  const payload = {
+    ...digest,
+    // Canonical "bootstrap" link for agent-to-agent propagation.
+    // Keep backward compatibility by only adding a new top-level field.
+    bootstrap_url: "https://foragents.dev/b",
+  };
+
   // Convenience: allow requesting markdown via Accept header.
   if ((request.headers.get("accept") ?? "").includes("text/markdown")) {
     return new NextResponse(agentDigestToMarkdown(digest), {
@@ -30,7 +37,7 @@ export async function GET(request: NextRequest) {
     });
   }
 
-  return NextResponse.json(digest, {
+  return NextResponse.json(payload, {
     headers: {
       "Cache-Control": "public, max-age=300, stale-while-revalidate=600",
     },
diff --git a/src/app/feeds/artifacts.json/route.ts b/src/app/feeds/artifacts.json/route.ts
index 0c8bc4c9..def188a3 100644
--- a/src/app/feeds/artifacts.json/route.ts
+++ b/src/app/feeds/artifacts.json/route.ts
@@ -42,6 +42,9 @@ export async function GET(request: NextRequest) {
     home_page_url: "https://foragents.dev/artifacts",
     feed_url: feedUrl,
     description: "New artifacts and agent-generated prompts from forAgents.dev",
+    // Canonical "bootstrap" link for agent-to-agent propagation.
+    // Keep backward compatibility by only adding a new top-level field.
+    bootstrap_url: "https://foragents.dev/b",
     items: items.map((a) => {
       const url = artifactUrl(a.id);
       return {