feat(diff): per-diff terminal width, auto_resize_terminal opt-out, and lifecycle events

[ThomasK33]

Summary

Closes #242.

Currently terminal.split_width_percentage controls the Claude terminal width both when idle and while a diff is open, coupling two preferences that often want different values (wide for chatting, narrow while reviewing a diff). This PR adds three layered, fully backward-compatible controls:

1. terminal.diff_split_width_percentage (default nil) — optional terminal width while a diff is open. Falls back to split_width_percentage when unset, so behavior is unchanged by default. This is the zero-Lua path for the original request.
2. diff_opts.auto_resize_terminal (default true) — when false, the plugin leaves the terminal width untouched across the diff lifecycle so you can own it yourself.
3. User autocmds ClaudeCodeDiffOpened / ClaudeCodeDiffClosed (always emitted, pcall-guarded) carrying a data payload — so configs can react to diffs opening/closing (resize, relayout, statusline, etc.) without monkey-patching private functions. This mirrors the existing ClaudeCodeSendComplete event convention added in [BUG] focus_after_send has no effect with provider = "none" #228.

The five existing terminal-resize sites are consolidated behind a single gated helper (resize_terminal_for_diff); the events fire exactly once per open/close at the single setup/cleanup points, so they also cover the :q-reject (#266) and disconnect-auto-close (#248) paths.

Design notes

This follows the triage discussion on #242: events are the durable, idiomatic mechanism (same shape as diffview.nvim's DiffviewViewOpened/Closed and this plugin's own ClaudeCodeSendComplete), with the width key as convenient sugar and the opt-out flag as the clean "I own the layout" escape hatch. Nothing is removed and the default behavior is byte-identical.

event.data for ClaudeCodeDiffOpened: tab_name, file_path, new_file_path, is_new_file, diff_window, target_window, terminal_window, tab_number. For ClaudeCodeDiffClosed: tab_name, file_path, reason (a best-effort human-readable label, not a stable enum).

Opt-out + event example

require("claudecode").setup({
  diff_opts = { auto_resize_terminal = false },
})

vim.api.nvim_create_autocmd("User", {
  pattern = "ClaudeCodeDiffOpened",
  callback = function(ev)
    local term = ev.data.terminal_window
    if term and vim.api.nvim_win_is_valid(term) then
      vim.api.nvim_win_set_width(term, math.floor(vim.o.columns * 0.20))
    end
  end,
})

Test plan

• mise run all — full suite green, lint + format clean.
• New unit tests: width resolution/fallback (diff_split_width_spec), auto_resize_terminal gate + resize_terminal_for_diff gating (enabled/disabled/floating/invalid/nil) + lifecycle-event payloads via the recorder convention (diff_auto_resize_events_spec), plus config/terminal validation for the new options.
• Headless Neovim integration (real diff open/close): both events fire with correct payloads; auto_resize_terminal=true shrinks the terminal to the diff width and restores the idle width on close; =false leaves width untouched while events still fire.
• Live interactive verification (real TUI): diff open shrank the terminal to 20% and restored to 50% on close; with auto_resize_terminal=false a user ClaudeCodeDiffOpened handler owned the width instead.

Docs

README gains a "Diff Lifecycle Events" section and the new config options; CLAUDE.md, dev-config.lua, and type annotations updated.

🤖 Generated with Claude Code

[ThomasK33]

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[ThomasK33]

Rebased onto latest main and CI is green (unit + integration tests pass). Please review the current commit (d4bfab3).

@claude review

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Reviewed commit: d4bfab3402

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[ThomasK33]

@codex review

Re-requesting on c88184e — the earlier P1 (stale-commit test) and P2 (opt-out docs wording) are both addressed and CI is green (unit + integration).

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep it up!

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Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

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