Callisto Pr

Callisto

Java Agent that captures runtime exceptions, classifies them as **INTERNAL** (your code) or **EXTERNAL** (dependency/API/IO/network), and opens GitHub Draft PRs with AI-generated fixes — all without touching a single line of your project.

your-app.jar  ──►  -javaagent:callisto.jar
                         │
                         ▼
                   captures exceptions
                         │
                         ▼
               .callisto/bugs.jsonl
                         │
              ┌──────────┼──────────┐
              ▼          ▼          ▼
          summary       show     draft-pr
          (stats)    (details)  (GitHub PR)

---

Requirements

Requirement	Purpose
Java 11+	Agent and CLI
GITHUB_TOKEN with repo scope	draft-pr command
claude CLI (authenticated)	draft-pr patch generation — install

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Installation

**Option A — pre-built JAR (recommended)**

Download `callisto.jar` from the [Releases](../../releases) page.

**Option B — build from source**

git clone https://github.com/yourorg/callisto
cd callisto
mvn clean package -DskipTests
# Output: callisto-agent/target/callisto.jar

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Usage

**1. Attach the agent to your JVM**

java -javaagent:/path/to/callisto.jar -jar your-app.jar

Callisto captures every exception silently in the background. No code changes needed.

**2. View captured bugs**

java -jar callisto.jar summary

Callisto Summary
================
Total bugs:  12

By classification:
  INTERNAL      4  (████     33%)
  EXTERNAL      7  (██████   58%)
  UNCERTAIN     1  (█         8%)

Top exception types:
  NullPointerException          3
  HttpConnectTimeoutException   2

**3. Inspect a bug**

java -jar callisto.jar show BUG-a1b2c3

Bug BUG-a1b2c3
==============
Exception    : java.lang.NullPointerException
Message      : Cannot invoke "String.toUpperCase()" becaus