feat(web): add optional PR/MR summary comment to review agent

.devcontainer/docker-compose.yml

@@ -27,6 +27,7 @@ services:
       REVIEW_AGENT_LOGGING_ENABLED: "true"
       REVIEW_AGENT_AUTO_REVIEW_ENABLED: "false"
       REVIEW_AGENT_REVIEW_COMMAND: review
+      REVIEW_AGENT_SUMMARY_ENABLED: "false"
     depends_on:
       - postgres
       - redis

.env.development

@@ -49,6 +49,7 @@ REDIS_URL="redis://localhost:6379"
 REVIEW_AGENT_LOGGING_ENABLED=true
 REVIEW_AGENT_AUTO_REVIEW_ENABLED=false
 REVIEW_AGENT_REVIEW_COMMAND=review
+REVIEW_AGENT_SUMMARY_ENABLED=false
 
 # Misc
 

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- [Experimental] Added support for generating a summary comment to the AI Code review agent. [#1175](https://github.com/sourcebot-dev/sourcebot/pull/1175)
+
 ## [4.17.1] - 2026-05-04
 
 ### Added

docs/docs/configuration/environment-variables.mdx

@@ -74,6 +74,8 @@ The following environment variables allow you to configure your Sourcebot deploy
 | `REVIEW_AGENT_AUTO_REVIEW_ENABLED` | `false` | <p>Enables/disables automatic code reviews by the review agent.</p> |
 | `REVIEW_AGENT_LOGGING_ENABLED` | `true` | <p>Enables/disables logging for the review agent. Logs are saved in `DATA_CACHE_DIR/review-agent`</p> |
 | `REVIEW_AGENT_REVIEW_COMMAND` | `review` | <p>The command used to trigger a code review by the review agent.</p> |
+| `REVIEW_AGENT_SUMMARY_ENABLED` | `false` | <p>Enables/disables posting a concise summary comment on the PR/MR after each review.</p> |
+| `REVIEW_AGENT_SUMMARY_MAX_LENGTH` | `250` | <p>Maximum character length of the summary comment posted by the review agent.</p> |
 
 ### Overriding environment variables from the config
 

docs/docs/features/agents/review-agent.mdx

@@ -145,3 +145,5 @@ You can also trigger a review manually by commenting `/review` on any PR or MR.
 | `REVIEW_AGENT_REVIEW_COMMAND` | `review` | Comment command that triggers a manual review (without the `/`) |
 | `REVIEW_AGENT_MODEL` | first configured model | `displayName` of the language model to use for reviews |
 | `REVIEW_AGENT_LOGGING_ENABLED` | unset | Write prompt and response logs to disk for debugging |
+| `REVIEW_AGENT_SUMMARY_ENABLED` | `false` | Post a concise summary comment on the PR/MR after each review |
+| `REVIEW_AGENT_SUMMARY_MAX_LENGTH` | `250` | Maximum character length of the summary comment |

packages/shared/src/env.server.ts

@@ -240,6 +240,8 @@ const options = {
         REVIEW_AGENT_LOGGING_ENABLED: booleanSchema.default('true'),
         REVIEW_AGENT_AUTO_REVIEW_ENABLED: booleanSchema.default('false'),
         REVIEW_AGENT_REVIEW_COMMAND: z.string().default('review'),
+        REVIEW_AGENT_SUMMARY_ENABLED: booleanSchema.default('false'),
+        REVIEW_AGENT_SUMMARY_MAX_LENGTH: numberSchema.default(250),
 
         ANTHROPIC_API_KEY: z.string().optional(),
         ANTHROPIC_AUTH_TOKEN: z.string().optional(),

packages/web/src/features/agents/review-agent/app.ts

@@ -1,12 +1,13 @@
 import { Octokit } from "octokit";
 import { Gitlab } from "@gitbeaker/rest";
 import { generatePrReviews } from "@/features/agents/review-agent/nodes/generatePrReview";
+import { generatePrSummary } from "@/features/agents/review-agent/nodes/generatePrSummary";
 import { githubPushPrReviews } from "@/features/agents/review-agent/nodes/githubPushPrReviews";
 import { githubPrParser } from "@/features/agents/review-agent/nodes/githubPrParser";
 import { getReviewAgentLogDir } from "@/features/agents/review-agent/nodes/invokeDiffReviewLlm";
 import { gitlabMrParser } from "@/features/agents/review-agent/nodes/gitlabMrParser";
 import { gitlabPushMrReviews } from "@/features/agents/review-agent/nodes/gitlabPushMrReviews";
-import { GitHubPullRequest, GitLabMergeRequestPayload } from "@/features/agents/review-agent/types";
+import { GitHubPullRequest, GitLabMergeRequestPayload, sourcebot_pr_payload } from "@/features/agents/review-agent/types";
 import { env } from "@sourcebot/shared";
 import path from "path";
 import fs from "fs";
@@ -24,6 +25,18 @@ const rules = [
 
 const logger = createLogger('review-agent');
 
+async function generateSummarySafely(payload: sourcebot_pr_payload, label: string): Promise<string | undefined> {
+    if (!env.REVIEW_AGENT_SUMMARY_ENABLED) {
+        return undefined;
+    }
+    try {
+        return await generatePrSummary(payload);
+    } catch (error) {
+        logger.error(`Error generating ${label} summary: ${error}`);
+        return undefined;
+    }
+}
+
 function getReviewAgentLogPath(identifier: string): string | undefined {
     if (!env.REVIEW_AGENT_LOGGING_ENABLED) {
         return undefined;
@@ -55,7 +68,9 @@ export async function processGitHubPullRequest(octokit: Octokit, pullRequest: Gi
 
     const prPayload = await githubPrParser(octokit, pullRequest);
     const fileDiffReviews = await generatePrReviews(reviewAgentLogPath, prPayload, rules);
-    await githubPushPrReviews(octokit, prPayload, fileDiffReviews);
+
+    const summary = await generateSummarySafely(prPayload, "PR");
+    await githubPushPrReviews(octokit, prPayload, fileDiffReviews, summary);
 }
 
 export async function processGitLabMergeRequest(
@@ -70,5 +85,7 @@ export async function processGitLabMergeRequest(
 
     const prPayload = await gitlabMrParser(gitlabClient, mrPayload, hostDomain);
     const fileDiffReviews = await generatePrReviews(reviewAgentLogPath, prPayload, rules);
-    await gitlabPushMrReviews(gitlabClient, projectId, prPayload, fileDiffReviews);
+
+    const summary = await generateSummarySafely(prPayload, "MR");
+    await gitlabPushMrReviews(gitlabClient, projectId, prPayload, fileDiffReviews, summary);
 }

packages/web/src/features/agents/review-agent/nodes/generatePrSummary.ts

@@ -0,0 +1,51 @@
+import { sourcebot_pr_payload } from "@/features/agents/review-agent/types";
+import { getAISDKLanguageModelAndOptions, getConfiguredLanguageModels } from "@/features/chat/utils.server";
+import { env } from "@sourcebot/shared";
+import { generateText } from "ai";
+import { createLogger } from "@sourcebot/shared";
+
+const logger = createLogger('generate-pr-summary');
+
+export const generatePrSummary = async (prPayload: sourcebot_pr_payload): Promise<string> => {
+    const maxSummaryLength = env.REVIEW_AGENT_SUMMARY_MAX_LENGTH;
+    logger.debug("Executing generate_pr_summary");
+
+    const models = await getConfiguredLanguageModels();
+    if (models.length === 0) {
+        throw new Error("No language models are configured");
+    }
+
+    let selectedModel = models[0];
+    if (env.REVIEW_AGENT_MODEL) {
+        const match = models.find((m) => m.displayName === env.REVIEW_AGENT_MODEL);
+        if (match) {
+            selectedModel = match;
+        } else {
+            logger.warn(`REVIEW_AGENT_MODEL="${env.REVIEW_AGENT_MODEL}" did not match any configured model displayName. Falling back to the first configured model.`);
+        }
+    }
+
+    const { model, providerOptions, temperature } = await getAISDKLanguageModelAndOptions(selectedModel);
+
+    const filesChanged = prPayload.file_diffs.map(f => f.to).join(", ");
+
+    const prompt = `Summarize the following pull request changes in ${maxSummaryLength} characters or fewer. Be concise and focus on what changed and why. You may use inline markdown (e.g. \`code\`, **bold**) but avoid headers, bullet lists, and block-level formatting.
+
+PR Title: ${prPayload.title}
+PR Description: ${prPayload.description}
+Files changed: ${filesChanged}
+`;
+
+    const result = await generateText({
+        model,
+        system: `You are a code review assistant. Generate a concise markdown-compatible summary of pull request changes. The summary must be ${maxSummaryLength} characters or fewer. Avoid headers, bullet lists, and block-level formatting.`,
+        prompt,
+        providerOptions,
+        temperature,
+    });
+
+    const summary = result.text.trim().slice(0, maxSummaryLength);
+
+    logger.debug("Completed generate_pr_summary");
+    return summary;
+};

packages/web/src/features/agents/review-agent/nodes/githubPushPrReviews.test.ts

@@ -29,14 +29,19 @@ const SINGLE_REVIEW: sourcebot_file_diff_review[] = [
     },
 ];
 
-function makeMockOctokit(createReviewCommentResult: 'resolve' | 'reject' = 'resolve') {
+function makeMockOctokit(createReviewCommentResult: 'resolve' | 'reject' = 'resolve', existingComments: { id: number; body: string }[] = []) {
     return {
         rest: {
             pulls: {
                 createReviewComment: createReviewCommentResult === 'resolve'
                     ? vi.fn().mockResolvedValue({})
                     : vi.fn().mockRejectedValue(new Error('Unprocessable Entity')),
             },
+            issues: {
+                listComments: vi.fn().mockResolvedValue({ data: existingComments }),
+                createComment: vi.fn().mockResolvedValue({}),
+                updateComment: vi.fn().mockResolvedValue({}),
+            },
         },
     } as any;
 }
@@ -146,3 +151,62 @@ describe('githubPushPrReviews', () => {
         expect(octokit.rest.pulls.createReviewComment).not.toHaveBeenCalled();
     });
 });
+
+describe('githubPushPrReviews – summary comment', () => {
+    const SUMMARY_MARKER = '<!-- sourcebot-review-summary -->';
+
+    test('does not call issues API when summary is undefined', async () => {
+        const octokit = makeMockOctokit();
+
+        await githubPushPrReviews(octokit, MOCK_PAYLOAD, [], undefined);
+
+        expect(octokit.rest.issues.listComments).not.toHaveBeenCalled();
+        expect(octokit.rest.issues.createComment).not.toHaveBeenCalled();
+        expect(octokit.rest.issues.updateComment).not.toHaveBeenCalled();
+    });
+
+    test('creates a new comment including the marker when no existing comment found', async () => {
+        const octokit = makeMockOctokit('resolve', []);
+
+        await githubPushPrReviews(octokit, MOCK_PAYLOAD, [], 'Summary text');
+
+        expect(octokit.rest.issues.listComments).toHaveBeenCalledWith({
+            owner: 'my-org',
+            repo: 'my-repo',
+            issue_number: 7,
+        });
+        expect(octokit.rest.issues.createComment).toHaveBeenCalledOnce();
+        const body = octokit.rest.issues.createComment.mock.calls[0][0].body as string;
+        expect(body).toContain(SUMMARY_MARKER);
+        expect(body).toContain('Summary text');
+        expect(body).toContain('Created:');
+        expect(body).not.toContain('Updated:');
+        expect(octokit.rest.issues.updateComment).not.toHaveBeenCalled();
+    });
+
+    test('updates the existing comment when the marker is already present', async () => {
+        const existingComments = [{ id: 99, body: `${SUMMARY_MARKER}\nOld summary` }];
+        const octokit = makeMockOctokit('resolve', existingComments);
+
+        await githubPushPrReviews(octokit, MOCK_PAYLOAD, [], 'New summary');
+
+        expect(octokit.rest.issues.updateComment).toHaveBeenCalledOnce();
+        expect(octokit.rest.issues.updateComment).toHaveBeenCalledWith(
+            expect.objectContaining({ comment_id: 99 }),
+        );
+        const body = octokit.rest.issues.updateComment.mock.calls[0][0].body as string;
+        expect(body).toContain('New summary');
+        expect(body).toContain('Updated:');
+        expect(body).not.toContain('Created:');
+        expect(octokit.rest.issues.createComment).not.toHaveBeenCalled();
+    });
+
+    test('does not throw when listComments fails', async () => {
+        const octokit = makeMockOctokit();
+        octokit.rest.issues.listComments = vi.fn().mockRejectedValue(new Error('403 Forbidden'));
+
+        await expect(
+            githubPushPrReviews(octokit, MOCK_PAYLOAD, [], 'Summary text'),
+        ).resolves.not.toThrow();
+    });
+});

packages/web/src/features/agents/review-agent/nodes/githubPushPrReviews.ts

@@ -4,9 +4,40 @@ import { createLogger } from "@sourcebot/shared";
 
 const logger = createLogger('github-push-pr-reviews');
 
-export const githubPushPrReviews = async (octokit: Octokit, pr_payload: sourcebot_pr_payload, file_diff_reviews: sourcebot_file_diff_review[]) => {
+export const githubPushPrReviews = async (octokit: Octokit, pr_payload: sourcebot_pr_payload, file_diff_reviews: sourcebot_file_diff_review[], summary?: string) => {
     logger.info("Executing github_push_pr_reviews");
 
+    if (summary) {
+        const SUMMARY_MARKER = "<!-- sourcebot-review-summary -->";
+        try {
+            const { data: comments } = await octokit.rest.issues.listComments({
+                owner: pr_payload.owner,
+                repo: pr_payload.repo,
+                issue_number: pr_payload.number,
+            });
+            const existing = comments.find(c => c.body?.includes(SUMMARY_MARKER));
+            const action = existing ? "Updated" : "Created";
+            const body = `${SUMMARY_MARKER}\n${summary}\n\n---\n*${action}: ${new Date().toUTCString()}*`;
+            if (existing) {
+                await octokit.rest.issues.updateComment({
+                    owner: pr_payload.owner,
+                    repo: pr_payload.repo,
+                    comment_id: existing.id,
+                    body,
+                });
+            } else {
+                await octokit.rest.issues.createComment({
+                    owner: pr_payload.owner,
+                    repo: pr_payload.repo,
+                    issue_number: pr_payload.number,
+                    body,
+                });
+            }
+        } catch (error) {
+            logger.error(`Error posting PR summary comment: ${error}`);
+        }
+    }
+
     try {
         for (const file_diff_review of file_diff_reviews) {
             for (const review of file_diff_review.reviews) {

packages/web/src/features/agents/review-agent/nodes/gitlabPushMrReviews.test.ts

@@ -34,15 +34,17 @@ const SINGLE_REVIEW: sourcebot_file_diff_review[] = [
     },
 ];
 
-function makeMockClient(discussionResult: 'resolve' | 'reject' = 'resolve') {
+function makeMockClient(discussionResult: 'resolve' | 'reject' = 'resolve', existingNotes: { id: number; body: string }[] = []) {
     return {
         MergeRequestDiscussions: {
             create: discussionResult === 'resolve'
                 ? vi.fn().mockResolvedValue({})
                 : vi.fn().mockRejectedValue(new Error('400 Bad Request')),
         },
         MergeRequestNotes: {
+            all: vi.fn().mockResolvedValue(existingNotes),
             create: vi.fn().mockResolvedValue({}),
+            edit: vi.fn().mockResolvedValue({}),
         },
     } as any;
 }
@@ -177,11 +179,63 @@ describe('gitlabPushMrReviews', () => {
     test('does not throw when both discussion and note creation fail', async () => {
         const client = {
             MergeRequestDiscussions: { create: vi.fn().mockRejectedValue(new Error('500')) },
-            MergeRequestNotes: { create: vi.fn().mockRejectedValue(new Error('500')) },
+            MergeRequestNotes: { all: vi.fn().mockResolvedValue([]), create: vi.fn().mockRejectedValue(new Error('500')), edit: vi.fn() },
         } as any;
 
         await expect(
             gitlabPushMrReviews(client, 101, MOCK_PAYLOAD, SINGLE_REVIEW),
         ).resolves.not.toThrow();
     });
 });
+
+describe('gitlabPushMrReviews – summary note', () => {
+    const SUMMARY_MARKER = '<!-- sourcebot-review-summary -->';
+
+    test('does not call MergeRequestNotes API when summary is undefined', async () => {
+        const client = makeMockClient();
+
+        await gitlabPushMrReviews(client, 101, MOCK_PAYLOAD, [], undefined);
+
+        expect(client.MergeRequestNotes.all).not.toHaveBeenCalled();
+        expect(client.MergeRequestNotes.create).not.toHaveBeenCalled();
+        expect(client.MergeRequestNotes.edit).not.toHaveBeenCalled();
+    });
+
+    test('creates a new note including the marker when no existing note found', async () => {
+        const client = makeMockClient('resolve', []);
+
+        await gitlabPushMrReviews(client, 101, MOCK_PAYLOAD, [], 'Summary text');
+
+        expect(client.MergeRequestNotes.all).toHaveBeenCalledWith(101, 42);
+        expect(client.MergeRequestNotes.create).toHaveBeenCalledOnce();
+        const body = client.MergeRequestNotes.create.mock.calls[0][2] as string;
+        expect(body).toContain(SUMMARY_MARKER);
+        expect(body).toContain('Summary text');
+        expect(body).toContain('Created:');
+        expect(body).not.toContain('Updated:');
+        expect(client.MergeRequestNotes.edit).not.toHaveBeenCalled();
+    });
+
+    test('updates the existing note when the marker is already present', async () => {
+        const existingNotes = [{ id: 55, body: `${SUMMARY_MARKER}\nOld summary` }];
+        const client = makeMockClient('resolve', existingNotes);
+
+        await gitlabPushMrReviews(client, 101, MOCK_PAYLOAD, [], 'New summary');
+
+        expect(client.MergeRequestNotes.edit).toHaveBeenCalledOnce();
+        const editOptions = client.MergeRequestNotes.edit.mock.calls[0][3] as { body: string };
+        expect(editOptions.body).toContain('New summary');
+        expect(editOptions.body).toContain('Updated:');
+        expect(editOptions.body).not.toContain('Created:');
+        expect(client.MergeRequestNotes.create).not.toHaveBeenCalled();
+    });
+
+    test('does not throw when MergeRequestNotes.all fails', async () => {
+        const client = makeMockClient();
+        client.MergeRequestNotes.all = vi.fn().mockRejectedValue(new Error('403 Forbidden'));
+
+        await expect(
+            gitlabPushMrReviews(client, 101, MOCK_PAYLOAD, [], 'Summary text'),
+        ).resolves.not.toThrow();
+    });
+});