session-time-machine

Early access. Claude Mods load in Claude Code >= 2.1.259 with CLAUDE_CODE_ENABLE_FUNCTION_HOOKS=1; the $ API may change between releases.

/timemachine draws the session as a timeline: every prompt, tool call and turn end, read from the session's own transcript. Press a point, type what you want done differently, and the mod writes a copy of the session cut at that point under a new session id and gives you the command that continues it. The session you are in is not touched, so you can try the other approach and still go back.

⏱ Time machine
 9 points  3 prompts  5 calls
──────────────────────────────────────
  1 ┏ ● prompt 1  add a retry to the upload client
  2 ┃ ◆ Read  src/upload.ts
  3 ┃ ◆ Edit  src/upload.ts                  <- armed (highlighted row)
  4 ┃ ◆ Bash  npm test
  5 ┗ ■ turn end  Tests pass, retry added with backoff.
╭────────────────────────────────────╮
│ Fork from #3                       │
│ after: src/upload.ts               │
│ Type the new instruction after     │
│ /timemachine fork 3 and press Enter│
╰────────────────────────────────────╯
↑ older   ↓ newer   ⟳ reload   ✕ clear

Colors mark the kind: blue prompts, violet turn ends, and a glyph per tool (green Bash, amber Edit/Write, teal Read/Grep/Glob, orange Web, pink Agent, lilac MCP). The armed row is highlighted and rows light up under the pointer.

> /timemachine fork 3 keep the retry but use the existing queue helper instead
Forked at point 3 (Edit src/upload.ts): 41 rows kept.
New session 7c1e…, resume command copied. In a new terminal:
cd '/home/me/app' && claude --resume 7c1e… 'keep the retry but use the existing queue helper instead'

Usage

Points are of three kinds. ▸ prompt: the fork keeps everything before that prompt, so the instruction replaces it. · tool call: the fork keeps the conversation up to and including that call's result. ■ turn end: the fork keeps the whole turn. The timeline refreshes when a turn completes; the pane's reload button re-reads it on demand.

How it forks, and what it cannot do

The mod API (checked against the declarations Claude Code 2.1.288 writes; the repo copy at types/claude-code.d.ts is 2.1.283) has no call that forks or rewinds the live session. $.model.fork is a tool-less side question over the transcript, and $.session offers messages, append, compact and send, none of which branches. So the fork is a new session, not a branch inside the one you are in:

1. the mod reads ~/.claude/projects/<project>/<session-id>.jsonl (or under CLAUDE_CONFIG_DIR) with $.fs.read,
2. follows the parentUuid chain back from the last row, which drops rewound branches and subagent sidechains,
3. keeps the rows up to the chosen point, extended so no tool_use it keeps is left without its tool_result,
4. writes them under a new id next to the original with $.fs.write,
5. returns claude --resume <new-id> '<instruction>', copied to the clipboard. Run it in a new terminal.

The resumed session starts from the cut with the instruction as its next message. Verified by hand on Claude Code 2.1.288: a fork cut at a tool call resumed with claude -p --resume and answered from the context at that point.

Limits:

• You open the fork yourself. The mod cannot start another Claude Code session; it hands you the command.
• Files are not rewound. The fork restores the conversation, not the working tree. If the original session already edited files after the cut, the fork's model will not know; use git (or a worktree) to reset them.
• 4 MiB. $.fs.read rejects files over 4 MiB, so a very long transcript shows an error in the pane instead of a timeline.
• Rows only. The timeline is the transcript's prompts, tool calls and turn ends; thinking and attachments are kept in the fork but not listed.
• Pane not drawn in claude -p. /timemachine list and fork work there; the pane needs the terminal UI.

Options

Read from user settings, keyed by the plugin's full id:

{ "pluginConfigs": { "session-time-machine@skills-dir": { "options": { "copyCommand": false } } } }

Install

npx claude-code-templates@latest --mod productivity/session-time-machine

Hooks: session.start (registers /timemachine), command.run, turn.complete, ui.render on Pane. Calls: $.fs.read, $.fs.write, $.env.get (HOME, CLAUDE_CONFIG_DIR), $.session.cwd, $.session.id, $.prompt.fill, $.ui.copy. No network, no process spawn.

Tests: CLAUDE_CODE_ENABLE_FUNCTION_HOOKS=1 claude plugin test productivity/session-time-machine cover the transcript parsing, the cut points, the tool-pair closing, the resume command, and mount the pane on the terminal and desktop surfaces to press a point.