diff --git a/src/context.ts b/src/context.ts
index 55f4c39..b9e3655 100644
--- a/src/context.ts
+++ b/src/context.ts
@@ -7,7 +7,14 @@ import type { Database } from "bun:sqlite";
 import { getWorkflowById } from "./db";
 import type { AdapterConfig, BundleArtifactRecord, Profile, ReplayGrade, TaskRecord, RuntimeConfig } from "./types";
 
-const MAX_PAYLOAD_CHARS = 4000;
+/**
+ * Default cap on characters used when summarizing the task payload for the
+ * prompt. Profiles can override via `context_policy.max_payload_chars` when
+ * they need to ship larger evidence payloads (e.g., curated PR diffs for
+ * review tasks). Kept conservative to preserve prior behavior for profiles
+ * that do not opt in.
+ */
+export const DEFAULT_MAX_PAYLOAD_CHARS = 4000;
 
 function sanitizeRelativeArtifactPath(value: string): string {
   return value
@@ -40,8 +47,8 @@ function truncateText(value: string, maxChars: number): string {
   return `${value.slice(0, Math.max(0, maxChars - 16))}\n[truncated]\n`;
 }
 
-function summarizeJson(value: Record<string, unknown>): string {
-  return truncateText(JSON.stringify(value, null, 2), MAX_PAYLOAD_CHARS);
+function summarizeJson(value: Record<string, unknown>, maxChars: number = DEFAULT_MAX_PAYLOAD_CHARS): string {
+  return truncateText(JSON.stringify(value, null, 2), maxChars);
 }
 
 function buildBundleTaskSnapshot(task: TaskRecord): Record<string, unknown> {
@@ -200,7 +207,7 @@ function buildGoalLoopContextLines(config: RuntimeConfig, task: TaskRecord): str
 }
 
 function buildPromptText(config: RuntimeConfig, profile: Profile, task: TaskRecord): string {
-  const payloadBlock = summarizeJson(task.payload);
+  const payloadBlock = summarizeJson(task.payload, profile.context_policy.max_payload_chars);
   const phaseSkills = Array.isArray(task.payload.phase_skills)
     ? task.payload.phase_skills.filter((value): value is string => typeof value === "string" && value.trim().length > 0)
     : [];
diff --git a/src/runtime.test.ts b/src/runtime.test.ts
index 69cb432..a4719c5 100644
--- a/src/runtime.test.ts
+++ b/src/runtime.test.ts
@@ -792,6 +792,56 @@ test("goal loop context no longer inlines oversized artifact content", async ()
   expect(context).not.toContain("tail");
 });
 
+test("payload truncates to default 4000 chars when context_policy does not override max_payload_chars", () => {
+  const config = testConfig();
+  const longString = "x".repeat(8000);
+  const profile = testProfile();
+  const context = assembleContext(config, profile, testTaskRecord({
+    payload: { evidence: longString }
+  }));
+
+  expect(context).toContain("[truncated]");
+  // Default cap is 4000; the payload block should not contain the full 8000-char value.
+  expect(context).not.toContain("x".repeat(8000));
+});
+
+test("payload respects context_policy.max_payload_chars override when profile sets it higher", () => {
+  const config = testConfig();
+  const longString = "y".repeat(8000);
+  const profile = testProfile({
+    context_policy: {
+      include_recent_task_memory: true,
+      max_prompt_chars: 32000,
+      max_payload_chars: 12000
+    }
+  });
+  const context = assembleContext(config, profile, testTaskRecord({
+    payload: { evidence: longString }
+  }));
+
+  // With a 12000-char payload cap, the full 8000-char value fits without truncation.
+  expect(context).toContain("y".repeat(8000));
+  expect(context).not.toContain("[truncated]");
+});
+
+test("payload respects context_policy.max_payload_chars override when profile sets it lower", () => {
+  const config = testConfig();
+  const longString = "z".repeat(2000);
+  const profile = testProfile({
+    context_policy: {
+      include_recent_task_memory: true,
+      max_prompt_chars: 16000,
+      max_payload_chars: 1000
+    }
+  });
+  const context = assembleContext(config, profile, testTaskRecord({
+    payload: { evidence: longString }
+  }));
+
+  expect(context).toContain("[truncated]");
+  expect(context).not.toContain("z".repeat(2000));
+});
+
 test("artifact-writing context requires declared managed artifact paths in artifact_paths", () => {
   const config = testConfig();
   const context = assembleContext(config, testProfile(), testTaskRecord({
diff --git a/src/types.ts b/src/types.ts
index 7b8785d..ab47176 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -82,6 +82,13 @@ export type Profile = {
   context_policy: {
     include_recent_task_memory: boolean;
     max_prompt_chars: number;
+    /**
+     * Maximum characters used when summarizing the task payload for the prompt.
+     * Optional; defaults to the runtime-internal `DEFAULT_MAX_PAYLOAD_CHARS`
+     * (currently 4000) when unset. Profiles that need to ship larger evidence
+     * payloads (curated diffs, structured review excerpts) can raise this.
+     */
+    max_payload_chars?: number;
   };
   result_schema: Record<string, boolean | string>;
   integration_policies: Record<string, string>;