Ticket to PR example (#592)

# Motivation

<!-- Why is this change necessary? -->

# Content
Adding an example of using the codegen sdk and event decorators to build
a quick Linear to PR bot integration
<!-- Please include a summary of the change -->

# Testing

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# Please check the following before marking your PR as ready for review

- [ ] I have added tests for my changes
- [ ] I have updated the documentation or added new documentation as
needed

---------

Co-authored-by: rushilpatel0 <[email protected]>

Author: rushilpatel0

codegen-examples/examples/ticket-to-pr/.env.template

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+LINEAR_ACCESS_TOKEN="..."
+LINEAR_SIGNING_SECRET="..."
+LINEAR_TEAM_ID="..."
+GITHUB_TOKEN="..."
+ANTHROPIC_API_KEY="..."

codegen-examples/examples/ticket-to-pr/README.md

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+# Linear Ticket to GitHub PR Bot
+
+This example project demonstrates how to deploy an agentic bot that automatically creates GitHub Pull Requests from Linear tickets. The bot leverages Linear's webhook system to listen for ticket updates and uses AI to generate corresponding GitHub PRs with appropriate code changes.
+
+## Prerequisites
+
+Before running this application, you'll need the following API tokens and credentials:
+
+- GitHub API Token
+- Linear API Token
+- Anthropic API Token
+- Linear Signing Key
+- Linear Team ID
+
+## Setup
+
+1. Clone the repository
+1. Set up your environment variables in a `.env` file:
+
+```env
+GITHUB_TOKEN=your_github_token
+LINEAR_API_TOKEN=your_linear_token
+ANTHROPIC_API_KEY=your_anthropic_token
+LINEAR_SIGNING_KEY=your_linear_signing_key
+LINEAR_TEAM_ID=your_team_id
+```
+
+## Features
+
+- Automatic PR creation from Linear tickets
+- AI-powered code generation using an agentic approach
+- Webhook integration with Linear
+
+## Usage
+
+1. uv sync
+1. uv run modal deploy app.py
+   - At this point you should have a modal app with an endpoint that is auto registered to linear as a webhook callback url.
+1. Try making a ticket and adding the `Codegen` label to trigger the agent
+
+## Contributing
+
+Contributions are welcome! Please feel free to submit a Pull Request.

codegen-examples/examples/ticket-to-pr/app.py

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+from codegen import Codebase, CodeAgent
+from codegen.extensions.clients.linear import LinearClient
+from codegen.extensions.events.app import CodegenApp
+from codegen.extensions.tools.github.create_pr import create_pr
+from codegen.shared.enums.programming_language import ProgrammingLanguage
+from helpers import create_codebase, format_linear_message, has_codegen_label, process_update_event
+
+from fastapi import Request
+
+import os
+import modal
+import logging
+
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+image = modal.Image.debian_slim(python_version="3.13").apt_install("git").pip_install("fastapi[standard]", "codegen>=v0.26.3")
+
+app = CodegenApp("linear-bot", image=image, modal_api_key="")
+
+
+@app.cls(secrets=[modal.Secret.from_dotenv()], keep_warm=1)
+class LinearApp:
+    codebase: Codebase
+
+    @modal.enter()
+    def run_this_on_container_startup(self):
+        self.codebase = create_codebase("codegen-sh/codegen-sdk", ProgrammingLanguage.PYTHON)
+
+        # Subscribe web endpoints as linear webhook callbacks
+        app.linear.subscribe_all_handlers()
+
+    @modal.exit()
+    def run_this_on_container_exit(self):
+        app.linear.unsubscribe_all_handlers()
+
+    @modal.web_endpoint(method="POST")
+    @app.linear.event("Issue", should_handle=has_codegen_label)
+    def handle_webhook(self, data: dict, request: Request):
+        """"Handle incoming webhook events from Linear""" ""
+        linear_client = LinearClient(access_token=os.environ["LINEAR_ACCESS_TOKEN"])
+
+        event = process_update_event(data)
+        linear_client.comment_on_issue(event.issue_id, "I'm on it 👍")
+
+        query = format_linear_message(event.title, event.description)
+        agent = CodeAgent(self.codebase)
+
+        agent.run(query)
+
+        pr_title = f"[{event.identifier}] " + event.title
+        pr_body = "Codegen generated PR for issue: " + event.issue_url
+        create_pr_result = create_pr(self.codebase, pr_title, pr_body)
+
+        logger.info(f"PR created: {create_pr_result.model_dump_json()}")
+
+        linear_client.comment_on_issue(event.issue_id, f"I've finished running, please review the PR: {create_pr_result.url}")
+        self.codebase.reset()
+
+        return {"status": "success"}

codegen-examples/examples/ticket-to-pr/data.py

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+from typing import Any, Dict, List, Optional
+from pydantic import BaseModel
+
+
+class LinearLabels(BaseModel):
+    id: str
+    color: str  # hex color
+    name: str
+
+
+class LinearIssueUpdateEvent(BaseModel):
+    action: str
+    issue_id: str
+    actor: Dict[str, Any]
+    created_at: str
+    issue_url: str
+    data: Dict[str, Any]
+    labels: List[LinearLabels]
+    updated_from: Dict[str, Any]
+    title: str
+    description: Optional[str] = None
+    identifier: Optional[str] = None

codegen-examples/examples/ticket-to-pr/helpers.py

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+from codegen import Codebase, ProgrammingLanguage
+from typing import List, Dict, Any
+from codegen.sdk.codebase.config import CodebaseConfig
+from data import LinearLabels, LinearIssueUpdateEvent
+import os
+import logging
+
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+
+def process_update_event(event_data: dict[str, Any]):
+    print("processing update event")
+
+    action = event_data.get("action")
+    actor = event_data.get("actor")
+    created_at = event_data.get("createdAt")
+    issue_url = event_data.get("url")
+    data: Dict[str, Any] = event_data.get("data")
+    issue_id = data.get("id")
+    title = data.get("title")
+    description = data.get("description")
+    identifier = data.get("identifier")
+
+    labels: List[LinearLabels] = data.get("labels")
+    updated_from: Dict[str, Any] = event_data.get("updatedFrom")
+
+    update_event = LinearIssueUpdateEvent(
+        issue_id=issue_id,
+        action=action,
+        actor=actor,
+        created_at=created_at,
+        issue_url=issue_url,
+        data=data,
+        labels=labels,
+        updated_from=updated_from,
+        title=title,
+        description=description,
+        identifier=identifier,
+    )
+    return update_event
+
+
+def format_linear_message(title: str, description: str | None = "") -> str:
+    """Format a Linear update event into a message for the agent"""
+
+    return f"""
+    Here is a new issue titled '{title}' and with the description '{description}'. Continue to respond to this query. Use your tools to query the codebase for more context.
+    When applicable include references to files and line numbers, code snippets are also encouraged. Don't forget to create a pull request with your changes, use the appropriate tool to do so.
+    """
+
+
+def has_codegen_label(*args, **kwargs):
+    body = kwargs.get("data")
+    type = body.get("type")
+    action = body.get("action")
+
+    if type == "Issue" and action == "update":
+        # handle issue update (label updates)
+        update_event = process_update_event(body)
+
+    has_codegen_label = any(label.name == "Codegen" for label in update_event.labels)
+    codegen_label_id = next((label.id for label in update_event.labels if label.name == "Codegen"), None)
+    had_codegen_label = codegen_label_id in update_event.updated_from.get("labels", []) if codegen_label_id else False
+    previous_labels = update_event.updated_from.get("labelIds", None)
+
+    if previous_labels is None or not has_codegen_label:
+        logger.info("No labels updated, skipping codegen bot response")
+        return False
+
+    if has_codegen_label and not had_codegen_label:
+        logger.info("Codegen label added, codegen bot will respond")
+        return True
+
+    logger.info("Codegen label removed or already existed, codegen bot will not respond")
+    return False
+
+
+def create_codebase(repo_name: str, language: ProgrammingLanguage):
+    config = CodebaseConfig()
+    config.secrets.github_token = os.environ["GITHUB_TOKEN"]
+
+    return Codebase.from_repo(repo_name, language=language, tmp_dir="/root", config=config)

codegen-examples/examples/ticket-to-pr/pyproject.toml

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+[project]
+name = "ticket-to-pr"
+version = "0.1.0"
+description = "A example implementation of a agentic linear bot that can create PRs from linear tickets"
+readme = "README.md"
+requires-python = ">=3.12, <3.14"
+dependencies = [
+  "codegen==0.26.3",
+  "fastapi>=0.115.8",
+  "modal>=0.73.51",
+  "pydantic>=2.10.6",
+]