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Jujutsu Juggler jjj

Change Tracking

Change ID Tracking

jjj leverages Jujutsu’s stable Change IDs to maintain metadata consistency even as the underlying Git commit history is rewritten.

The Problem with Git Commit IDs

In standard Git, every time you rebase, amend, or squash, the commit hash changes. If project metadata (like a link between a task and a branch) relies on commit hashes, it breaks constantly.

graph TD
    subgraph "Git Problem"
        A[Commit hash: abc123] --> B[Rebase/Amend]
        B --> C[New hash: def456]
        D[Metadata linked to abc123] -.->|BROKEN| C
    end

The Jujutsu Solution: Change IDs

Jujutsu introduces a stable Change ID that remains constant even if the commit hash changes during a rebase. jjj uses these Change IDs to anchor solutions to the logical work being performed.

graph TD
    subgraph "jjj + Jujutsu Solution"
        A[Change ID: pmmz-qxrv<br/>Commit: abc123] --> B[Rebase/Amend]
        B --> C[Change ID: pmmz-qxrv<br/>Commit: def456]
        D[Solution linked to pmmz-qxrv] -->|STABLE| C
    end

How the Mapping Works

When you run jjj solution attach, jjj records the current change ID in the solution’s internal metadata:

# solution file
id: 01958c4d-...
title: Implement caching
status: testing
change_ids:
  - pmmz-qxrv  # Stable Jujutsu Change ID

Automatic Attachment

When you use jjj solution resume "Implement caching", jjj does the following:

  1. Creates a new jj change.
  2. Captures the Change ID of that new change.
  3. Automatically appends it to the solution’s change_ids list.

Multi-Change Solutions

A single solution can span multiple jj changes. jjj tracks all of them, allowing the dashboard to show you everything related to a conjecture regardless of how many individual commits or changes it involves.

Benefits

  • Robust Rebasing: You can rebase your feature branch as much as you want; jjj will never lose track of which solution that code belongs to.
  • No Manual Bookkeeping: The stable mapping happens automatically behind the scenes.
  • Contextual Status: By knowing which code belongs to which problem, jjj status can provide a high-level view of your progress that reflects the actual state of your workspace.