GitHub PR → LLM review → comment

Automate first-pass pull request reviews without posting unreviewed AI text to your repo. The workflow fetches PR metadata and diffs, drafts a review with an LLM, pauses for human approval in Command Center, then posts an approved comment on GitHub.

What you’ll build

Outcome: Reviewers see a structured summary in Command Center, edit or reject it, and only approved text is published as a GitHub comment.

Prerequisites

project_contributor access
GitHub personal access token with repo scope on target repositories
LLM provider configured in Providers
Optional: inbound webhook from GitHub (pull_request events) or manual runs with owner, repo, pr_number

Connectors to install

Adapter	Purpose
github	Read PR, list files, post comment

Build the workflow

Create workflow

Name it github-pr-review in Workflow Studio.

Validate input

lua_script requires owner, repo, and pr_number.

Fetch PR and files

Chain mcp_call → get_pull_request then list_pull_request_files.

LLM review

llm_call with PR title, body, and file list in the prompt. Ask for risks, test gaps, and a suggested comment body.

Human approval

human_task with task_type: "approval" showing the draft comment. See Human tasks.

Post comment

mcp_call → add_issue_comment using the LLM draft text, gated by {{steps.approve-review.result.approved}}.

Trigger

Start runs manually, via API, or wire a GitHub webhook to an inbound subscription that maps pull_request.number to pr_number.

Validate input

{
  "id": "validate",
  "type": "lua_script",
  "name": "Validate PR coordinates",
  "script": "if not input.owner or not input.repo or not input.pr_number then error('owner, repo, pr_number required') end\nreturn {\n  owner = input.owner,\n  repo = input.repo,\n  pr_number = tonumber(input.pr_number)\n}",
  "timeout_s": 10
}

Fetch PR

{
  "id": "get-pr",
  "type": "mcp_call",
  "name": "Get pull request",
  "tool_name": "get_pull_request",
  "tool_args": {
    "owner": "{{steps.validate.result.owner}}",
    "repo": "{{steps.validate.result.repo}}",
    "pull_number": "{{steps.validate.result.pr_number}}"
  },
  "depends_on": ["validate"],
  "timeout_s": 30
}

List changed files

{
  "id": "list-files",
  "type": "mcp_call",
  "name": "List PR files",
  "tool_name": "list_pull_request_files",
  "tool_args": {
    "owner": "{{steps.validate.result.owner}}",
    "repo": "{{steps.validate.result.repo}}",
    "pull_number": "{{steps.validate.result.pr_number}}"
  },
  "depends_on": ["get-pr"],
  "timeout_s": 30
}

LLM review

{
  "id": "draft-review",
  "type": "llm_call",
  "name": "Draft PR review",
  "model": "gpt-4o",
  "prompt": "You are a senior engineer reviewing a pull request.\n\nTitle: {{steps.get-pr.result.title}}\nDescription: {{steps.get-pr.result.body}}\nFiles changed: {{steps.list-files.result}}\n\nWrite a concise review comment (markdown) covering: summary, risks, testing suggestions, and approval recommendation. Output only the comment body.",
  "depends_on": ["list-files"],
  "timeout_s": 180
}

Human approval

{
  "id": "approve-review",
  "type": "human_task",
  "name": "Approve review comment",
  "task_type": "approval",
  "task_payload": {
    "title": "Post PR review on {{steps.validate.result.owner}}/{{steps.validate.result.repo}}#{{steps.validate.result.pr_number}}",
    "description": "Edit or reject before posting to GitHub.",
    "draft_body": "{{steps.draft-review.result.text}}"
  },
  "depends_on": ["draft-review"],
  "timeout_s": 86400
}

Post comment

{
  "id": "post-comment",
  "type": "mcp_call",
  "name": "Add GitHub comment",
  "tool_name": "add_issue_comment",
  "tool_args": {
    "owner": "{{steps.validate.result.owner}}",
    "repo": "{{steps.validate.result.repo}}",
    "issue_number": "{{steps.validate.result.pr_number}}",
    "body": "{{steps.draft-review.result.text}}"
  },
  "depends_on": ["approve-review"],
  "condition": "{{steps.approve-review.result.approved}}",
  "timeout_s": 30
}

Command Approve only sets approved: true on the human task step — it does not copy draft_body into the result. Reference the LLM step for comment text, or complete the task via API with a custom result object. See Human tasks.

Full workflow graph (copy-paste)

Replace tenant_id, workflow_id, and bind your github MCP instance on each mcp_call step in Workflow Studio (instance picker sets server_url at publish time).

{
  "tenant_id": "your-workspace-slug",
  "workflow_id": "550e8400-e29b-41d4-a716-446655440010",
  "params": {},
  "steps": [
    {
      "id": "validate",
      "type": "lua_script",
      "name": "Validate PR coordinates",
      "script": "if not input.owner or not input.repo or not input.pr_number then error('owner, repo, pr_number required') end\nreturn {\n  owner = input.owner,\n  repo = input.repo,\n  pr_number = tonumber(input.pr_number)\n}",
      "timeout_s": 10
    },
    {
      "id": "get-pr",
      "type": "mcp_call",
      "name": "Get pull request",
      "tool_name": "get_pull_request",
      "tool_args": {
        "owner": "{{steps.validate.result.owner}}",
        "repo": "{{steps.validate.result.repo}}",
        "pull_number": "{{steps.validate.result.pr_number}}"
      },
      "depends_on": ["validate"],
      "timeout_s": 30
    },
    {
      "id": "list-files",
      "type": "mcp_call",
      "name": "List PR files",
      "tool_name": "list_pull_request_files",
      "tool_args": {
        "owner": "{{steps.validate.result.owner}}",
        "repo": "{{steps.validate.result.repo}}",
        "pull_number": "{{steps.validate.result.pr_number}}"
      },
      "depends_on": ["get-pr"],
      "timeout_s": 30
    },
    {
      "id": "draft-review",
      "type": "llm_call",
      "name": "Draft PR review",
      "model": "gpt-4o",
      "prompt": "You are a senior engineer reviewing a pull request.\n\nTitle: {{steps.get-pr.result.title}}\nDescription: {{steps.get-pr.result.body}}\nFiles changed: {{steps.list-files.result}}\n\nWrite a concise review comment (markdown) covering: summary, risks, testing suggestions, and approval recommendation. Output only the comment body.",
      "depends_on": ["list-files"],
      "timeout_s": 180
    },
    {
      "id": "approve-review",
      "type": "human_task",
      "name": "Approve review comment",
      "task_type": "approval",
      "task_payload": {
        "title": "Post PR review on {{steps.validate.result.owner}}/{{steps.validate.result.repo}}#{{steps.validate.result.pr_number}}",
        "description": "Review the draft in Command Center. Reject to cancel the GitHub comment.",
        "draft_body": "{{steps.draft-review.result.text}}"
      },
      "depends_on": ["draft-review"],
      "timeout_s": 86400
    },
    {
      "id": "post-comment",
      "type": "mcp_call",
      "name": "Add GitHub comment",
      "tool_name": "add_issue_comment",
      "tool_args": {
        "owner": "{{steps.validate.result.owner}}",
        "repo": "{{steps.validate.result.repo}}",
        "issue_number": "{{steps.validate.result.pr_number}}",
        "body": "{{steps.draft-review.result.text}}"
      },
      "depends_on": ["approve-review"],
      "condition": "{{steps.approve-review.result.approved}}",
      "timeout_s": 30
    }
  ]
}

Start a run via Workflow Studio or:

POST /v1/workflows/{id}/command
{ "command": "start", "params": { "owner": "your-org", "repo": "your-repo", "pr_number": 42 } }

Test run

Start a manual run:

{
  "owner": "your-org",
  "repo": "your-repo",
  "pr_number": 42
}

Open Command Center, approve or edit the draft, then confirm the comment appears on the PR.

Variations

Add compare_commits for larger diff context before the LLM step.
Route low-confidence reviews: Lua checks for “BLOCK” in LLM output → always require human task.
On approval, call merge_pull_request instead of commenting (separate workflow with stricter gates).

Get started

Platform

Workflows

Guides

Integration setup

Connectors

AI & chat

API

GitHub PR → LLM review → comment

What you’ll build

Prerequisites

Connectors to install

Build the workflow

Validate input

Fetch PR

List changed files

LLM review

Human approval

Post comment

Full workflow graph (copy-paste)

Test run

Variations

​What you’ll build

​Prerequisites

​Connectors to install

​Build the workflow

​Validate input

​Fetch PR

​List changed files

​LLM review

​Human approval

​Post comment

​Full workflow graph (copy-paste)

​Test run

​Variations

​Related

What you’ll build

Prerequisites

Connectors to install

Build the workflow

Validate input

Fetch PR

List changed files

LLM review

Human approval

Post comment

Full workflow graph (copy-paste)

Test run

Variations

Related