Replay Theater Claude Code mod: a Claude Code diff viewer for the last turn

Replay Theater is a community mod by Hamza Zafar (hamzafer), part of his claude-code-mods collection. It works as a small Claude Code diff viewer for the last turn. While Claude edits files, the mod notes each Edit and Write call: the file, the old text and the new text. When the turn ends, you get a toast, replay-theater: 2 edits last turn. Run /replay, and /replay opens a pane called Replay Theater.

The pane shows Step 1/2, the kind of change (edit or write) and the file path relative to your working directory. A row of step numbers marks where you are, and Prev, Next and Close buttons (hotkeys p, n and q) move through the steps. Below them is a line diff: removed lines in red with a -, added lines in green with a +, unchanged lines dimmed. After the first toast in a session, later turns show ▶ /replay: N edits in the status line instead, and the count clears when the next turn starts.

For a Write, the mod reads the file just before it is overwritten, so a replaced file shows a real before and after. Diffs larger than 800 lines in total are not drawn; the pane says large change and shows the line counts instead.

Use any of the methods in the install block; they install straight from the author's own marketplace. Start a new session, ask Claude to edit a file, and run /replay when the turn ends.

The mod keeps the edits of the current turn in a list, and copies it to host-held $.state atoms when the turn completes, so a replay survives a hot reload. The Edit hook, from hooks/register.tsx:

// Observe only: the edit runs untouched.
on('tool.call', { tool: 'Edit' }, async ($, e, next) => {
  const r = await next(e)
  if (!r.deny && !r.isError) {
    pending.push({ file: e.file_path, kind: 'edit', before: e.old_string, after: e.new_string })
  }
  return r
})

turn.start empties the pending list, and turn.complete (main agent only, and only if something was recorded) stores it as the replay and shows the toast or status line. command.run for replay opens the pane with $.ui.open, and the pane's ui.render hook draws the current step. The diff itself is a small longest-common-subsequence line diff, diffLines, in the same file. The session.start hook registers /replay; if Claude Code refuses the name because it already exists, the mod starts anyway.

There are no options in /config. To change it, edit hooks/register.tsx: MAX_DIFF_LINES sets the size at which a diff is not drawn, and the color props in the pane set the diff colors. The /replay command name is set in the session.start hook.

We read every file the plugin can execute before running it: .claude-plugin/plugin.json, hooks/hooks.json, hooks/register.tsx, the type declarations and the tests. There is no package.json, install script, bundled or minified code, or binary. Findings:

• Network, processes, environment, telemetry: none. The code makes no network requests, runs no commands, reads no environment variables and sends nothing anywhere.
• Files: the only file access is $.fs.read of the target path of a Write call, just before the write, to show a before text. The mod never writes files. Edit and write contents are held in memory only. Anything Claude writes, including a file that contains secrets, is held in memory for the session while it is in the last turn's replay.
• Tool hooks: the Edit and Write hooks wrap next(e) and return the result unchanged; they never deny or alter a call. claude plugin validate lists them as "gating hooks without .catch", which means that if the mod threw an error inside the hook, the tool call could fail. The code in these hooks does only a push to an array, and the read before Write has its own .catch.
• Prompt influence: none. It injects no text into the prompt or tool results; it only draws a pane, a toast and a status line.
• Daemons, writes to settings or shell files: none.
• License: MIT, with a LICENSE file in the repository.

claude plugin validate reported no errors and no warnings. The author's 3 tests passed on Claude Code 2.1.303.

Checked with Claude Code 2.1.303 on macOS (validate and tests). If /replay shows nothing:

• You see No edits to replay yet when the last turn used no Edit or Write call. Edits made through shell commands are not recorded.
• The first turn of a session shows a toast; later turns use the status line, which clears when the next turn starts.
• If Claude Code already has a command called replay, the mod could not register it. The author's code starts anyway, but the command may not exist.
• In our test run the hotkeys p, n and q went to the prompt box. Click the pane's buttons, or give it focus, before using them.

To try it, ask Claude for two small edits, wait for the toast replay-theater: 2 edits last turn. Run /replay, run /replay after the turn has finished, and step through both diffs.