diff --git a/CHANGELOG.md b/CHANGELOG.md
index 459145bf09ed..20481a145fc6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -85,6 +85,8 @@ Docs: https://docs.openclaw.ai
 - Providers/OpenRouter: stop adding empty DeepSeek V4 `reasoning_content` placeholders to assistant tool-call replay messages and strip empty replay artifacts before follow-up Chat Completions requests, so `openrouter/deepseek/deepseek-v4-pro` no longer fails after tool use. Fixes #82150. (#82158) Thanks @luyao618 and @Suquir0.
 - OpenAI-compatible providers: honor streaming-usage compatibility metadata when deciding whether to send `stream_options.include_usage`, while keeping bundled Volcengine routes opted in to Ark streaming usage. Refs #44845. (#82181) Thanks @xuruiray.
 - Gateway/approvals: treat `turnSourceTo` as optional in `canBridgeNoDeviceChatApprovalFromBackend`, matching the existing optional handling of `turnSourceAccountId` and `turnSourceThreadId`. Channels without a recipient concept (webchat, control-ui) leave `turnSourceTo` null on both the approval snapshot and the replay params, so the prior required-string check rejected every backend replay with `APPROVAL_CLIENT_MISMATCH`. Cross-channel replay is still gated by the required `turnSourceChannel` and `sessionKey` checks. Fixes #82132. (#82136) Thanks @ottodeng.
+- OC Path: add `openclaw path set --dry-run --diff` so addressed edits can be reviewed as a unified diff before writing.
+
 - Cron: load runtime plugins before isolated cron model and delivery resolution so external channels can be selected for scheduled runs. (#82111) Thanks @medns.
 - Cron: mirror successful direct scheduled deliveries into the resolved destination session transcript while preserving isolated-delivery awareness policy. (#80786) Thanks @cavit99.
 - Cron: preserve rotated transcript identity after session-bound scheduled runs compact, so `sessionTarget: "current"` keeps the next user message on the same conversation. Fixes #82164. Thanks @weissfl.
diff --git a/docs/cli/path.md b/docs/cli/path.md
index 1688c30c7963..8772e16dc7a0 100644
--- a/docs/cli/path.md
+++ b/docs/cli/path.md
@@ -135,6 +135,7 @@ matches you can inspect before choosing one to write.
 | `--json`        | Force JSON output (default when stdout is not a TTY).                    |
 | `--human`       | Force human output (default when stdout is a TTY).                       |
 | `--dry-run`     | (only on `set`) print the bytes that would be written without writing.   |
+| `--diff`        | (with `set --dry-run`) print a unified diff instead of the full bytes.   |
 
 ## `oc://` syntax
 
@@ -202,6 +203,8 @@ the per-kind AST shape.
 Use `--dry-run` before user-visible writes when the exact bytes matter. The
 substrate preserves byte-identical output for parse/emit round-trips, but a
 mutation can canonicalize the edited region or file depending on kind.
+Add `--diff` when you want the preview as a focused before/after patch instead
+of the full rendered file.
 
 ## Examples
 
@@ -218,6 +221,9 @@ openclaw path find 'oc://session.jsonl/*/event' --file ./logs/session.jsonl
 # Dry-run a write
 openclaw path set 'oc://gateway.jsonc/version' '2.0' --dry-run
 
+# Dry-run a write as a unified diff
+openclaw path set 'oc://gateway.jsonc/version' '2.0' --dry-run --diff
+
 # Apply the write
 openclaw path set 'oc://gateway.jsonc/version' '2.0'
 
@@ -375,12 +381,13 @@ openclaw path find 'oc://config.jsonc/plugins/{github,slack}/enabled'
 ### `set <oc-path> <value>`
 
 Write a leaf. Pair with `--dry-run` to preview the bytes that would be
-written without touching the file. Exits `0` on a successful write, `1` if
-the substrate refuses (for example, a sentinel guard hit), `2` on parse
-errors.
+written without touching the file. Add `--diff` for a unified diff preview.
+Exits `0` on a successful write, `1` if the substrate refuses (for example, a
+sentinel guard hit), `2` on parse errors.
 
 ```bash
 openclaw path set 'oc://gateway.jsonc/version' '2.0' --dry-run
+openclaw path set 'oc://gateway.jsonc/version' '2.0' --dry-run --diff
 openclaw path set 'oc://gateway.jsonc/version' '2.0'
 openclaw path set 'oc://AGENTS.md/Tools/+gh/risk' 'low'
 ```
diff --git a/extensions/oc-path/src/cli.test.ts b/extensions/oc-path/src/cli.test.ts
index 0b3a9fca018d..3cd8f46287a8 100644
--- a/extensions/oc-path/src/cli.test.ts
+++ b/extensions/oc-path/src/cli.test.ts
@@ -12,6 +12,7 @@ import { join } from "node:path";
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
 import {
   type OutputRuntimeEnv,
+  formatUnifiedDiff,
   pathEmitCommand,
   pathFindCommand,
   pathResolveCommand,
@@ -152,6 +153,92 @@ describe("openclaw path CLI", () => {
       expect(readFileSync(filePath, "utf-8")).toBe(before);
     });
 
+    it("CLI-S05 --dry-run --diff prints a unified diff", async () => {
+      const filePath = join(workspaceDir, "gateway.jsonc");
+      const before = '{\n  "version": "1.0",\n  "enabled": true\n}\n';
+      writeFileSync(filePath, before, "utf-8");
+      const rt = createTestRuntime();
+      await pathSetCommand(
+        "oc://gateway.jsonc/version",
+        "2.0",
+        { cwd: workspaceDir, human: true, dryRun: true, diff: true },
+        rt,
+      );
+      expect(rt.exitCode).toBe(0);
+      const out = stdoutText(rt);
+      expect(out).toContain("--- ");
+      expect(out).toContain("+++ ");
+      expect(out).toContain('-  "version": "1.0",');
+      expect(out).toContain('+  "version": "2.0",');
+      expect(readFileSync(filePath, "utf-8")).toBe(before);
+    });
+
+    it("CLI-S05b --dry-run --diff shows final newline-only byte changes", () => {
+      const out = formatUnifiedDiff(
+        "## Boundaries\n\n- timeout: 5\n",
+        "## Boundaries\n\n- timeout: 5",
+        "AGENTS.md",
+      );
+      expect(out).toContain("--- AGENTS.md");
+      expect(out).toContain("@@ -1,4 +1,3 @@");
+      expect(out).toContain("\n-\n");
+    });
+
+    it("CLI-S05c --dry-run --diff shows line-ending-only byte changes", async () => {
+      const filePath = join(workspaceDir, "AGENTS.md");
+      const before = "---\r\nname: x\r\n---\r\n";
+      writeFileSync(filePath, before, "utf-8");
+      const rt = createTestRuntime();
+      await pathSetCommand(
+        "oc://AGENTS.md/[frontmatter]/name",
+        "x",
+        { cwd: workspaceDir, json: true, dryRun: true, diff: true },
+        rt,
+      );
+      expect(rt.exitCode).toBe(0);
+      const out = JSON.parse(stdoutText(rt));
+      expect(out.diff).toContain("-name: x\r");
+      expect(out.diff).toContain("+name: x");
+      expect(readFileSync(filePath, "utf-8")).toBe(before);
+    });
+
+    it("CLI-S06 --dry-run --diff includes diff in JSON output", async () => {
+      const filePath = join(workspaceDir, "gateway.jsonc");
+      writeFileSync(filePath, '{ "version": "1.0" }', "utf-8");
+      const rt = createTestRuntime();
+      await pathSetCommand(
+        "oc://gateway.jsonc/version",
+        "2.0",
+        { cwd: workspaceDir, json: true, dryRun: true, diff: true },
+        rt,
+      );
+      expect(rt.exitCode).toBe(0);
+      const out = JSON.parse(stdoutText(rt));
+      expect(out.dryRun).toBe(true);
+      expect(out.bytes).toContain('"2.0"');
+      expect(out.diff).toContain('-{ "version": "1.0" }');
+      expect(out.diff).toContain('+{ "version": "2.0" }');
+    });
+
+    it("CLI-S07 rejects --diff without --dry-run", async () => {
+      const filePath = join(workspaceDir, "gateway.jsonc");
+      const before = '{ "version": "1.0" }';
+      writeFileSync(filePath, before, "utf-8");
+      const rt = createTestRuntime();
+      await pathSetCommand(
+        "oc://gateway.jsonc/version",
+        "2.0",
+        { cwd: workspaceDir, json: true, diff: true },
+        rt,
+      );
+      expect(rt.exitCode).toBe(1);
+      expect(JSON.parse(stdoutText(rt))).toMatchObject({
+        ok: false,
+        reason: "--diff requires --dry-run",
+      });
+      expect(readFileSync(filePath, "utf-8")).toBe(before);
+    });
+
     it("CLI-S03 sentinel-bearing value is refused at emit", async () => {
       const filePath = join(workspaceDir, "gateway.jsonc");
       writeFileSync(filePath, '{ "token": "x" }', "utf-8");
diff --git a/extensions/oc-path/src/cli.ts b/extensions/oc-path/src/cli.ts
index a0b8a99e7eaf..8c43b3572f5e 100644
--- a/extensions/oc-path/src/cli.ts
+++ b/extensions/oc-path/src/cli.ts
@@ -42,6 +42,7 @@ export interface PathCommandOptions {
   readonly cwd?: string;
   readonly file?: string;
   readonly dryRun?: boolean;
+  readonly diff?: boolean;
 }
 
 type OutputMode = "human" | "json";
@@ -63,13 +64,19 @@ const defaultRuntime: OutputRuntimeEnv = {
 // Defense-in-depth: replace the redaction sentinel with `[REDACTED]`
 // before writing, even if upstream emits it.
 export function scrubSentinel(s: string): string {
-  if (!s.includes(REDACTED_SENTINEL)) {return s;}
+  if (!s.includes(REDACTED_SENTINEL)) {
+    return s;
+  }
   return s.split(REDACTED_SENTINEL).join(SCRUB_PLACEHOLDER);
 }
 
 function detectMode(options: PathCommandOptions): OutputMode {
-  if (options.json === true) {return "json";}
-  if (options.human === true) {return "human";}
+  if (options.json === true) {
+    return "json";
+  }
+  if (options.human === true) {
+    return "human";
+  }
   return process.stdout.isTTY ? "human" : "json";
 }
 
@@ -116,11 +123,7 @@ function requireArg<T>(
 }
 
 /** Parse an oc-path string; emit structured error and return null on failure. */
-function tryParse(
-  pathStr: string,
-  runtime: OutputRuntimeEnv,
-  mode: OutputMode,
-): OcPath | null {
+function tryParse(pathStr: string, runtime: OutputRuntimeEnv, mode: OutputMode): OcPath | null {
   try {
     return parseOcPath(pathStr);
   } catch (err) {
@@ -157,8 +160,12 @@ function catchSentinel<T>(
 async function loadAst(absPath: string, fileName: string): Promise<OcAst> {
   const raw = await fs.readFile(absPath, "utf-8");
   const kind = inferKind(fileName);
-  if (kind === "jsonc") {return parseJsonc(raw).ast;}
-  if (kind === "jsonl") {return parseJsonl(raw).ast;}
+  if (kind === "jsonc") {
+    return parseJsonc(raw).ast;
+  }
+  if (kind === "jsonl") {
+    return parseJsonl(raw).ast;
+  }
   return parseMd(raw).ast;
 }
 
@@ -177,7 +184,9 @@ function emitForKind(ast: OcAst, fileName?: string): string {
 }
 
 function resolveFsPath(path: OcPath, options: PathCommandOptions): string {
-  if (options.file !== undefined) {return resolvePath(options.file);}
+  if (options.file !== undefined) {
+    return resolvePath(options.file);
+  }
   return resolvePath(options.cwd ?? process.cwd(), path.file);
 }
 
@@ -185,13 +194,72 @@ function formatMatchHuman(match: OcMatch): string {
   if (match.kind === "leaf") {
     return `leaf @ L${match.line}: ${JSON.stringify(match.valueText)} (${match.leafType})`;
   }
-  if (match.kind === "node") {return `node @ L${match.line} [${match.descriptor}]`;}
+  if (match.kind === "node") {
+    return `node @ L${match.line} [${match.descriptor}]`;
+  }
   if (match.kind === "insertion-point") {
     return `insertion-point @ L${match.line} [${match.container}]`;
   }
   return `root @ L${match.line}`;
 }
 
+function splitDiffLines(s: string): readonly string[] {
+  return s === "" ? [] : s.split("\n");
+}
+
+export function formatUnifiedDiff(oldBytes: string, newBytes: string, fsPath: string): string {
+  if (oldBytes === newBytes) {
+    return "";
+  }
+  const oldLines = splitDiffLines(oldBytes);
+  const newLines = splitDiffLines(newBytes);
+  let prefix = 0;
+  while (
+    prefix < oldLines.length &&
+    prefix < newLines.length &&
+    oldLines[prefix] === newLines[prefix]
+  ) {
+    prefix++;
+  }
+
+  let oldSuffix = oldLines.length - 1;
+  let newSuffix = newLines.length - 1;
+  while (
+    oldSuffix >= prefix &&
+    newSuffix >= prefix &&
+    oldLines[oldSuffix] === newLines[newSuffix]
+  ) {
+    oldSuffix--;
+    newSuffix--;
+  }
+
+  const context = 3;
+  const hunkStart = Math.max(0, prefix - context);
+  const hunkOldEnd = Math.min(oldLines.length - 1, oldSuffix + context);
+  const hunkNewEnd = Math.min(newLines.length - 1, newSuffix + context);
+  const oldCount = Math.max(0, hunkOldEnd - hunkStart + 1);
+  const newCount = Math.max(0, hunkNewEnd - hunkStart + 1);
+  const lines = [
+    `--- ${fsPath}`,
+    `+++ ${fsPath}`,
+    `@@ -${hunkStart + 1},${oldCount} +${hunkStart + 1},${newCount} @@`,
+  ];
+
+  for (let i = hunkStart; i < prefix; i++) {
+    lines.push(` ${oldLines[i] ?? ""}`);
+  }
+  for (let i = prefix; i <= oldSuffix; i++) {
+    lines.push(`-${oldLines[i] ?? ""}`);
+  }
+  for (let i = prefix; i <= newSuffix; i++) {
+    lines.push(`+${newLines[i] ?? ""}`);
+  }
+  for (let i = Math.max(oldSuffix + 1, prefix); i <= hunkOldEnd; i++) {
+    lines.push(` ${oldLines[i] ?? ""}`);
+  }
+  return `${lines.join("\n")}\n`;
+}
+
 // ---------- Commands -----------------------------------------------------
 
 export async function pathResolveCommand(
@@ -200,9 +268,13 @@ export async function pathResolveCommand(
   runtime: OutputRuntimeEnv,
 ): Promise<void> {
   const mode = detectMode(options);
-  if (!requireArg(pathStr, "resolve: missing <oc-path> argument", runtime, mode)) {return;}
+  if (!requireArg(pathStr, "resolve: missing <oc-path> argument", runtime, mode)) {
+    return;
+  }
   const ocPath = tryParse(pathStr, runtime, mode);
-  if (ocPath === null) {return;}
+  if (ocPath === null) {
+    return;
+  }
   const ast = await loadAst(resolveFsPath(ocPath, options), ocPath.file);
   let match: OcMatch | null;
   try {
@@ -231,15 +303,34 @@ export async function pathSetCommand(
   runtime: OutputRuntimeEnv,
 ): Promise<void> {
   const mode = detectMode(options);
-  if (!requireArg(pathStr, "set: requires <oc-path> <value>", runtime, mode)) {return;}
-  if (!requireArg(value, "set: requires <oc-path> <value>", runtime, mode)) {return;}
+  if (!requireArg(pathStr, "set: requires <oc-path> <value>", runtime, mode)) {
+    return;
+  }
+  if (!requireArg(value, "set: requires <oc-path> <value>", runtime, mode)) {
+    return;
+  }
+  if (options.diff === true && options.dryRun !== true) {
+    emit(
+      runtime,
+      mode,
+      { ok: false, reason: "--diff requires --dry-run" },
+      () => "set failed: --diff requires --dry-run",
+    );
+    runtime.exit(1);
+    return;
+  }
   const ocPath = tryParse(pathStr, runtime, mode);
-  if (ocPath === null) {return;}
+  if (ocPath === null) {
+    return;
+  }
   const fsPath = resolveFsPath(ocPath, options);
+  const oldBytes = await fs.readFile(fsPath, "utf-8");
   const ast = await loadAst(fsPath, ocPath.file);
 
   const result = catchSentinel("set", runtime, mode, () => setOcPath(ast, ocPath, value));
-  if (result === null) {return;}
+  if (result === null) {
+    return;
+  }
   if (!result.ok) {
     const detail = "detail" in result ? result.detail : undefined;
     emit(
@@ -252,17 +343,21 @@ export async function pathSetCommand(
     return;
   }
   // Per-kind emit can still refuse the sentinel even after set succeeds.
-  const newBytes = catchSentinel("emit", runtime, mode, () =>
-    emitForKind(result.ast, ocPath.file),
-  );
-  if (newBytes === null) {return;}
+  const newBytes = catchSentinel("emit", runtime, mode, () => emitForKind(result.ast, ocPath.file));
+  if (newBytes === null) {
+    return;
+  }
 
   if (options.dryRun === true) {
+    const diff = options.diff === true ? formatUnifiedDiff(oldBytes, newBytes, fsPath) : undefined;
     emit(
       runtime,
       mode,
-      { ok: true, dryRun: true, bytes: newBytes },
-      () => `--dry-run: would write ${newBytes.length} bytes to ${fsPath}\n${newBytes}`,
+      { ok: true, dryRun: true, bytes: newBytes, ...(diff !== undefined ? { diff } : {}) },
+      () =>
+        diff !== undefined
+          ? diff || `--dry-run: no byte changes for ${fsPath}`
+          : `--dry-run: would write ${newBytes.length} bytes to ${fsPath}\n${newBytes}`,
     );
     return;
   }
@@ -281,9 +376,13 @@ export async function pathFindCommand(
   runtime: OutputRuntimeEnv,
 ): Promise<void> {
   const mode = detectMode(options);
-  if (!requireArg(patternStr, "find: missing <pattern> argument", runtime, mode)) {return;}
+  if (!requireArg(patternStr, "find: missing <pattern> argument", runtime, mode)) {
+    return;
+  }
   const pattern = tryParse(patternStr, runtime, mode);
-  if (pattern === null) {return;}
+  if (pattern === null) {
+    return;
+  }
   // File-slot wildcards would silently ENOENT during readFile; reject.
   if (/[*?]/.test(pattern.file)) {
     emitError(
@@ -307,7 +406,9 @@ export async function pathFindCommand(
       matches: matches.map((m) => ({ path: formatOcPath(m.path), match: m.match })),
     },
     () => {
-      if (matches.length === 0) {return `0 matches for ${patternStr}`;}
+      if (matches.length === 0) {
+        return `0 matches for ${patternStr}`;
+      }
       const plural = matches.length === 1 ? "" : "es";
       const lines = [`${matches.length} match${plural} for ${patternStr}:`];
       for (const m of matches) {
@@ -316,7 +417,9 @@ export async function pathFindCommand(
       return lines.join("\n");
     },
   );
-  if (matches.length === 0) {runtime.exit(1);}
+  if (matches.length === 0) {
+    runtime.exit(1);
+  }
 }
 
 export function pathValidateCommand(
@@ -325,7 +428,9 @@ export function pathValidateCommand(
   runtime: OutputRuntimeEnv,
 ): void {
   const mode = detectMode(options);
-  if (!requireArg(pathStr, "validate: missing <oc-path> argument", runtime, mode)) {return;}
+  if (!requireArg(pathStr, "validate: missing <oc-path> argument", runtime, mode)) {
+    return;
+  }
   try {
     const ocPath = parseOcPath(pathStr);
     emit(
@@ -345,10 +450,18 @@ export function pathValidateCommand(
       },
       () => {
         const lines = [`valid: ${pathStr}`, `  file:    ${ocPath.file}`];
-        if (ocPath.section !== undefined) {lines.push(`  section: ${ocPath.section}`);}
-        if (ocPath.item !== undefined) {lines.push(`  item:    ${ocPath.item}`);}
-        if (ocPath.field !== undefined) {lines.push(`  field:   ${ocPath.field}`);}
-        if (ocPath.session !== undefined) {lines.push(`  session: ${ocPath.session}`);}
+        if (ocPath.section !== undefined) {
+          lines.push(`  section: ${ocPath.section}`);
+        }
+        if (ocPath.item !== undefined) {
+          lines.push(`  item:    ${ocPath.item}`);
+        }
+        if (ocPath.field !== undefined) {
+          lines.push(`  field:   ${ocPath.field}`);
+        }
+        if (ocPath.session !== undefined) {
+          lines.push(`  session: ${ocPath.session}`);
+        }
         return lines.join("\n");
       },
     );
@@ -373,7 +486,9 @@ export async function pathEmitCommand(
   runtime: OutputRuntimeEnv,
 ): Promise<void> {
   const mode = detectMode(options);
-  if (!requireArg(fileArg, "emit: missing <file> argument", runtime, mode)) {return;}
+  if (!requireArg(fileArg, "emit: missing <file> argument", runtime, mode)) {
+    return;
+  }
   const fsPath =
     options.file !== undefined
       ? resolvePath(options.file)
@@ -381,7 +496,9 @@ export async function pathEmitCommand(
   const fileName = fsPath.split(/[\\/]/).pop() ?? fileArg;
   const ast = await loadAst(fsPath, fileName);
   const bytes = catchSentinel("emit", runtime, mode, () => emitForKind(ast, fileName));
-  if (bytes === null) {return;}
+  if (bytes === null) {
+    return;
+  }
   if (mode === "json") {
     runtime.writeStdout(scrubSentinel(JSON.stringify({ ok: true, kind: ast.kind, bytes })));
     return;
@@ -429,7 +546,8 @@ export function registerPathCli(program: Command): void {
       .description("Write a leaf value at an oc:// path")
       .argument("<oc-path>", "oc:// path to write")
       .argument("<value>", "string value to write")
-      .option("--dry-run", "Print bytes without writing"),
+      .option("--dry-run", "Print bytes without writing")
+      .option("--diff", "With --dry-run, print a unified diff instead of full bytes"),
   ).action(async (pathStr: string, value: string, opts: PathCommandOptions) => {
     await pathSetCommand(pathStr, value, opts, defaultRuntime);
   });