Add rename history with undo

- New crates/renamr-core/src/history module: HistoryBatch/HistoryEntry
  records, revert_batch() moves files back to their original paths
  (skip-on-conflict, same policy as rename::execute_renames; recreates a
  deleted destination folder defensively), push_batch() maintains a
  most-recent-first log capped at 50 batches. A partial port of the idea
  behind net.filebot.HistoryDialog, as a flat undo stack rather than a full
  session/element log. 6 new tests.
- New src-tauri/src/history.rs: persists the log as history.json in the OS
  app-config directory (same location as settings.json). execute_rename now
  takes an AppHandle and calls history::record_batch after every rename,
  recording only the items that actually got renamed. Two new commands:
  list_rename_history and undo_rename_batch.
- Frontend: the History button (previously a no-op) now opens a panel
  listing past rename batches with a timestamp, file count, and the
  old-name/new-name pairs, each with an Undo button. Undoing reconciles any
  currently-loaded item back to its pre-rename path/name, same pattern as
  post-rename reconciliation.
- Verified via cargo test (45 total)/check + npm build + a full Playwright
  pass: loaded mocked files, renamed them, opened History, undid the batch,
  and confirmed both the UI and the (mocked) backend state matched at every
  step.

README.md

@@ -10,10 +10,11 @@ detection ("Match") is working, real online metadata lookups against TMDB ("Fetc
 Data") are working — including fuzzy show-name disambiguation, so a search that
 returns several similarly-named shows doesn't just take TMDB's top-ranked hit — and the
 actual on-disk rename operation is wired up (skip-on-conflict, with a confirmation step
-showing the full old-name/new-name plan before anything touches disk — there is no undo
-yet). Rename can also organize files into subfolders — including ones that don't exist
-yet — when the naming scheme includes a `/`. Full media-metadata bindings are not yet
-ported. See "Porting roadmap" below.
+showing the full old-path/new-path plan before anything touches disk). Rename can also
+organize files into subfolders — including ones that don't exist yet — when the naming
+scheme includes a `/`. Every completed rename is logged to a history panel that can
+undo it, moving files back to their original paths. Full media-metadata bindings are
+not yet ported. See "Porting roadmap" below.
 
 The naming scheme is fully user-editable from the app (the "Naming Scheme" button next
 to the New Names list) — the default is `{show name} - {season number}x{episode
@@ -110,23 +111,26 @@ crates/renamr-core/   Pure Rust core: naming-expression engine (ported), local
                        (`similarity/`, partial `EpisodeMetrics` port), a TMDB metadata
                        client (`web/tmdb.rs` — TV search + episode lookup, disambiguated
                        via `similarity/`, tested against a mocked HTTP server via
-                       `mockito`), and the on-disk rename engine (`rename/`) —
+                       `mockito`), the on-disk rename engine (`rename/`) —
                        skip-on-conflict, can also organize into (auto-created)
-                       subfolders when the naming scheme includes `/`. Not yet ported:
-                       full media metadata bindings, other web datasource clients
-                       (TVDB/AniDB/etc).
+                       subfolders when the naming scheme includes `/` — and a rename
+                       history/undo log (`history/`, a partial `HistoryDialog` port).
+                       Not yet ported: full media metadata bindings, other web
+                       datasource clients (TVDB/AniDB/etc).
                        No Tauri dependency, so it builds and unit-tests standalone.
 src-tauri/             Tauri app shell: exposes renamr-core as commands to the frontend
                        (naming-scheme rendering, filename matching, TMDB metadata fetch,
                        executing a rename plan, native file/folder dialogs, drag-and-drop
-                       expansion), plus `settings.rs` (TMDB token, stored as JSON in the
-                       OS app-config directory), app metadata/icons/window config
+                       expansion), plus `settings.rs` (TMDB token) and `history.rs`
+                       (rename history/undo log) — both stored as JSON in the OS
+                       app-config directory — app metadata/icons/window config
                        (tauri.conf.json).
 src/                   React + TypeScript UI (Vite). Faithful recreation of the original
                        two-pane rename screen (Aurora theme) wired to real file loading,
                        drag-and-drop, live naming-scheme preview, local matching, TMDB
-                       fetch (behind a Settings modal for the API token), and a
-                       confirm-before-touching-disk modal for the actual rename.
+                       fetch (behind a Settings modal for the API token), a
+                       confirm-before-touching-disk modal for the actual rename, and a
+                       History panel that can undo a past rename.
 scripts/gen_icons.py   Regenerates src-tauri/icons/ (placeholder branding — swap the
                        colors/glyph in the script, or replace the icons directly, to
                        change the look).
@@ -217,13 +221,18 @@ ported from, for anyone picking this up:
    `--conflict` variants beyond skip (auto-number, override), and the CLI flag surface
    itself.
 7. **The rest of the UI** — the Rename panel (file loading, drag-drop, live preview,
-   local matching, confirmed rename) is built; the other five sidebar panels
-   (Episodes/Subtitles/SFV/Filter/List) are still stub screens, plus Align up/down
-   reordering, History, and Presets on the Rename panel itself are no-ops. There's also
-   no per-item exclude inside the rename confirmation modal yet (it's all-or-nothing —
-   use "Exclude Selected" on the file list beforehand to leave a file out entirely).
-8. **Undo/history for renames** — there is no undo yet; the confirmation modal before
-   Rename executes is the only safety net right now. `net.filebot.HistoryDialog`/the
-   original's rename-history log is the reference for what a real undo would look like.
+   local matching, confirmed rename, rename history/undo) is built; the other five
+   sidebar panels (Episodes/Subtitles/SFV/Filter/List) are still stub screens, plus
+   Align up/down reordering and Presets on the Rename panel itself are still no-ops.
+   There's also no per-item exclude inside the rename confirmation modal yet (it's
+   all-or-nothing — use "Exclude Selected" on the file list beforehand to leave a file
+   out entirely).
+8. **Undo/history for renames** — done, as a flat JSON-backed undo stack rather than a
+   full port of `net.filebot.HistoryDialog`'s session/element log
+   (`crates/renamr-core/src/history`, `src-tauri/src/history.rs`). Every successful
+   rename is recorded to a `history.json` in the OS app-config directory (same location
+   as `settings.json`); the History panel lists past batches and can revert one back to
+   its original paths, skipping (never overwriting) any file whose original path now
+   has something else at it. Capped at the 50 most recent batches.
 9. **Packaging** — code signing, auto-update, installers per platform via
    `npm run tauri build`.

crates/renamr-core/src/history/mod.rs

@@ -0,0 +1,289 @@
+//! Rename history: a persisted log of past rename batches (what changed, from what to
+//! what) and the ability to revert one - Renamr's only safety net beyond the
+//! confirmation-before-execute step, since a plain filesystem rename has no OS-level
+//! undo. Loosely inspired by `net.filebot.HistoryDialog`/the original's rename-history
+//! log, but as a flat JSON-backed undo stack (see [`push_batch`]) rather than a full
+//! session/element log - simpler, and all this app actually needs.
+//!
+//! This module only implements the *logic* (recording, trimming, reverting); where the
+//! log is persisted to disk is a Tauri-layer concern (`src-tauri/src/history.rs`), same
+//! split as `rename` (pure logic here) vs. the Tauri command that calls it.
+
+use serde::{Deserialize, Serialize};
+use std::fs;
+use std::path::Path;
+
+/// One file's old path -> new path, as recorded right after a successful rename.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct HistoryEntry {
+    pub source: String,
+    pub new_path: String,
+}
+
+/// One executed rename operation - everything renamed together in a single "Rename N
+/// Files" confirmation - undoable as a unit.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct HistoryBatch {
+    pub id: String,
+    /// Unix epoch milliseconds when the batch was executed. Kept as a plain number
+    /// (no date/time dependency needed in this crate) so the frontend can format it
+    /// however it likes, e.g. `new Date(timestamp).toLocaleString()`.
+    pub timestamp: u64,
+    pub entries: Vec<HistoryEntry>,
+}
+
+/// What happened when reverting one entry of a batch.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
+#[serde(tag = "status", rename_all = "camelCase")]
+pub enum RevertOutcome {
+    /// Successfully moved back to its original path.
+    Reverted { restored_path: String },
+    /// A different file already exists at the original path; left untouched - the same
+    /// skip-never-overwrite policy `rename::execute_renames` uses.
+    SkippedConflict { existing_path: String },
+    /// The renamed file isn't where the history says it should be anymore (moved,
+    /// deleted, or already reverted some other way), or the OS reported an error.
+    Failed { error: String },
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct RevertResult {
+    /// The entry's `new_path` (i.e. where the file was expected to be found, before
+    /// reverting) - lets the caller map a result back to a specific history entry.
+    pub source: String,
+    pub outcome: RevertOutcome,
+}
+
+fn same_file(a: &Path, b: &Path) -> bool {
+    match (fs::canonicalize(a), fs::canonicalize(b)) {
+        (Ok(pa), Ok(pb)) => pa == pb,
+        _ => false,
+    }
+}
+
+fn revert_one(entry: &HistoryEntry) -> RevertOutcome {
+    let current = Path::new(&entry.new_path);
+    let original = Path::new(&entry.source);
+
+    if !current.exists() {
+        return RevertOutcome::Failed {
+            error: "the renamed file is no longer at its recorded location".to_string(),
+        };
+    }
+
+    if original.exists() && !same_file(original, current) {
+        return RevertOutcome::SkippedConflict {
+            existing_path: original.to_string_lossy().to_string(),
+        };
+    }
+
+    // The original's parent directory should still exist (nothing in Renamr deletes
+    // directories), but recreate it defensively in case it was removed by hand since -
+    // cheap, and `create_dir_all` is a no-op when it's already there.
+    if let Some(parent) = original.parent() {
+        if let Err(e) = fs::create_dir_all(parent) {
+            return RevertOutcome::Failed {
+                error: format!("couldn't recreate the original folder: {e}"),
+            };
+        }
+    }
+
+    match fs::rename(current, original) {
+        Ok(()) => RevertOutcome::Reverted {
+            restored_path: original.to_string_lossy().to_string(),
+        },
+        Err(e) => RevertOutcome::Failed { error: e.to_string() },
+    }
+}
+
+/// Reverts every entry in a batch, in order. Like [`crate::rename::execute_renames`],
+/// entries are processed sequentially (not in parallel) so a collision between two
+/// entries in the same batch resolves deterministically rather than racing.
+pub fn revert_batch(batch: &HistoryBatch) -> Vec<RevertResult> {
+    batch
+        .entries
+        .iter()
+        .map(|entry| RevertResult {
+            source: entry.new_path.clone(),
+            outcome: revert_one(entry),
+        })
+        .collect()
+}
+
+/// Maximum number of batches kept in the persisted history - once the log grows past
+/// this, the oldest batches are dropped so the history file can't grow unbounded over
+/// a long-lived install.
+pub const MAX_HISTORY_BATCHES: usize = 50;
+
+/// Adds a new batch to the front of `history` (most-recent-first) and trims the log
+/// back down to [`MAX_HISTORY_BATCHES`]. A batch with no entries is not recorded at
+/// all - a rename operation where every item was unchanged/skipped/failed has nothing
+/// to undo, so it shouldn't clutter the history.
+pub fn push_batch(history: &mut Vec<HistoryBatch>, batch: HistoryBatch) {
+    if batch.entries.is_empty() {
+        return;
+    }
+    history.insert(0, batch);
+    history.truncate(MAX_HISTORY_BATCHES);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::sync::atomic::{AtomicU32, Ordering};
+
+    static COUNTER: AtomicU32 = AtomicU32::new(0);
+
+    fn temp_dir() -> std::path::PathBuf {
+        let n = COUNTER.fetch_add(1, Ordering::SeqCst);
+        let dir = std::env::temp_dir().join(format!("renamr_history_test_{}_{}", std::process::id(), n));
+        fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+
+    #[test]
+    fn reverts_a_renamed_file_back_to_its_original_path() {
+        let dir = temp_dir();
+        let original = dir.join("Breaking.Bad.S05E14.mkv");
+        let renamed = dir.join("Ozymandias.mkv");
+        fs::write(&renamed, "video").unwrap();
+
+        let batch = HistoryBatch {
+            id: "b1".to_string(),
+            timestamp: 0,
+            entries: vec![HistoryEntry {
+                source: original.to_string_lossy().to_string(),
+                new_path: renamed.to_string_lossy().to_string(),
+            }],
+        };
+
+        let results = revert_batch(&batch);
+        match &results[0].outcome {
+            RevertOutcome::Reverted { restored_path } => {
+                assert_eq!(Path::new(restored_path), original.as_path());
+                assert!(original.exists());
+                assert!(!renamed.exists());
+            }
+            other => panic!("expected Reverted, got {other:?}"),
+        }
+
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn reverting_into_a_subfolder_target_recreates_a_deleted_original_folder() {
+        let dir = temp_dir();
+        let sub = dir.join("Breaking Bad");
+        fs::create_dir_all(&sub).unwrap();
+        let original = sub.join("Ozymandias.mkv");
+        let renamed = dir.join("flat.mkv");
+        fs::write(&renamed, "video").unwrap();
+        // Simulate the organized-into subfolder having been removed since the rename.
+        fs::remove_dir_all(&sub).unwrap();
+
+        let batch = HistoryBatch {
+            id: "b1".to_string(),
+            timestamp: 0,
+            entries: vec![HistoryEntry {
+                source: original.to_string_lossy().to_string(),
+                new_path: renamed.to_string_lossy().to_string(),
+            }],
+        };
+
+        let results = revert_batch(&batch);
+        assert!(matches!(results[0].outcome, RevertOutcome::Reverted { .. }));
+        assert!(original.exists());
+
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn skips_revert_when_something_else_now_occupies_the_original_path() {
+        let dir = temp_dir();
+        let original = dir.join("original.mkv");
+        fs::write(&original, "a new unrelated file").unwrap();
+        let renamed = dir.join("renamed.mkv");
+        fs::write(&renamed, "video").unwrap();
+
+        let batch = HistoryBatch {
+            id: "b1".to_string(),
+            timestamp: 0,
+            entries: vec![HistoryEntry {
+                source: original.to_string_lossy().to_string(),
+                new_path: renamed.to_string_lossy().to_string(),
+            }],
+        };
+
+        let results = revert_batch(&batch);
+        assert!(matches!(
+            results[0].outcome,
+            RevertOutcome::SkippedConflict { .. }
+        ));
+        // Neither file should have been touched.
+        assert_eq!(fs::read_to_string(&original).unwrap(), "a new unrelated file");
+        assert_eq!(fs::read_to_string(&renamed).unwrap(), "video");
+
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn fails_gracefully_when_the_renamed_file_is_no_longer_there() {
+        let dir = temp_dir();
+        let original = dir.join("original.mkv");
+        let renamed = dir.join("renamed.mkv"); // never created
+
+        let batch = HistoryBatch {
+            id: "b1".to_string(),
+            timestamp: 0,
+            entries: vec![HistoryEntry {
+                source: original.to_string_lossy().to_string(),
+                new_path: renamed.to_string_lossy().to_string(),
+            }],
+        };
+
+        let results = revert_batch(&batch);
+        assert!(matches!(results[0].outcome, RevertOutcome::Failed { .. }));
+
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn push_batch_ignores_empty_batches() {
+        let mut history = Vec::new();
+        push_batch(
+            &mut history,
+            HistoryBatch {
+                id: "empty".to_string(),
+                timestamp: 0,
+                entries: vec![],
+            },
+        );
+        assert!(history.is_empty());
+    }
+
+    #[test]
+    fn push_batch_orders_most_recent_first_and_trims_to_the_cap() {
+        let mut history = Vec::new();
+        for i in 0..(MAX_HISTORY_BATCHES + 5) {
+            push_batch(
+                &mut history,
+                HistoryBatch {
+                    id: format!("batch-{i}"),
+                    timestamp: i as u64,
+                    entries: vec![HistoryEntry {
+                        source: "a".to_string(),
+                        new_path: "b".to_string(),
+                    }],
+                },
+            );
+        }
+
+        assert_eq!(history.len(), MAX_HISTORY_BATCHES);
+        // Most recently pushed batch is first.
+        assert_eq!(history[0].id, format!("batch-{}", MAX_HISTORY_BATCHES + 4));
+        // The oldest batches (0..5) were dropped to stay under the cap.
+        assert!(!history.iter().any(|b| b.id == "batch-0"));
+    }
+}

crates/renamr-core/src/lib.rs

@@ -6,6 +6,7 @@
 //! parsing, web datasource clients, rename engine are not yet ported).
 
 pub mod format;
+pub mod history;
 pub mod matching;
 pub mod rename;
 pub mod similarity;

src-tauri/src/history.rs

@@ -0,0 +1,101 @@
+//! The Tauri-facing side of rename history/undo: persists the log
+//! `renamr_core::history` produces to disk (plain JSON in the OS app-config
+//! directory, alongside `settings.json`) and exposes it to the UI as two commands -
+//! list the log, and undo one batch from it.
+
+use renamr_core::history::{self, HistoryBatch, HistoryEntry, RevertResult};
+use renamr_core::rename::{RenameOutcome, RenameResult};
+use std::fs;
+use std::path::PathBuf;
+use std::time::{SystemTime, UNIX_EPOCH};
+use tauri::{AppHandle, Manager};
+
+fn history_path(app: &AppHandle) -> Result<PathBuf, String> {
+    let dir = app
+        .path()
+        .app_config_dir()
+        .map_err(|e| format!("couldn't resolve the app config directory: {e}"))?;
+    fs::create_dir_all(&dir).map_err(|e| format!("couldn't create {}: {e}", dir.display()))?;
+    Ok(dir.join("history.json"))
+}
+
+fn load(app: &AppHandle) -> Vec<HistoryBatch> {
+    let Ok(path) = history_path(app) else {
+        return Vec::new();
+    };
+    fs::read_to_string(path)
+        .ok()
+        .and_then(|contents| serde_json::from_str(&contents).ok())
+        .unwrap_or_default()
+}
+
+fn save(app: &AppHandle, batches: &[HistoryBatch]) -> Result<(), String> {
+    let path = history_path(app)?;
+    let json = serde_json::to_string_pretty(batches).map_err(|e| e.to_string())?;
+    fs::write(&path, json).map_err(|e| format!("couldn't write {}: {e}", path.display()))
+}
+
+fn now_millis() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|d| d.as_millis() as u64)
+        .unwrap_or(0)
+}
+
+/// Called right after a rename batch executes (see `execute_rename` in `lib.rs`) -
+/// records only the entries that were actually renamed; a file that was unchanged,
+/// skipped, or failed to rename has nothing to undo. Best-effort: if persisting the
+/// history fails for some reason, the rename itself already succeeded and shouldn't be
+/// reported as failed just because its undo record couldn't be saved, so errors here
+/// are swallowed rather than surfaced to the caller.
+pub fn record_batch(app: &AppHandle, results: &[RenameResult]) {
+    let entries: Vec<HistoryEntry> = results
+        .iter()
+        .filter_map(|r| match &r.outcome {
+            RenameOutcome::Renamed { new_path } => Some(HistoryEntry {
+                source: r.source.clone(),
+                new_path: new_path.clone(),
+            }),
+            _ => None,
+        })
+        .collect();
+
+    if entries.is_empty() {
+        return;
+    }
+
+    let batch = HistoryBatch {
+        id: format!("batch-{}", now_millis()),
+        timestamp: now_millis(),
+        entries,
+    };
+
+    let mut batches = load(app);
+    history::push_batch(&mut batches, batch);
+    let _ = save(app, &batches);
+}
+
+/// Lists every recorded rename batch, most-recent-first.
+#[tauri::command]
+pub fn list_rename_history(app: AppHandle) -> Vec<HistoryBatch> {
+    load(&app)
+}
+
+/// Reverts one batch (by id) and removes it from the history log - a batch is only
+/// ever undone once. Reverting is best-effort per file (see `RevertOutcome`): a file
+/// that's no longer where the history says, or whose original path now has something
+/// else at it, is reported rather than silently skipped, but doesn't block the rest of
+/// the batch from being reverted.
+#[tauri::command]
+pub fn undo_rename_batch(app: AppHandle, batch_id: String) -> Result<Vec<RevertResult>, String> {
+    let mut batches = load(&app);
+    let idx = batches
+        .iter()
+        .position(|b| b.id == batch_id)
+        .ok_or_else(|| "That rename batch isn't in the history log anymore.".to_string())?;
+    let batch = batches.remove(idx);
+
+    let results = history::revert_batch(&batch);
+    save(&app, &batches)?;
+    Ok(results)
+}

src-tauri/src/lib.rs

@@ -1,4 +1,5 @@
 mod files;
+mod history;
 mod metadata;
 mod settings;
 
@@ -7,6 +8,7 @@ use renamr_core::matching::{self, EpisodeGuess};
 use renamr_core::rename::{self, RenamePlanItem, RenameResult};
 use renamr_core::string_bindings;
 use std::collections::HashMap;
+use tauri::AppHandle;
 
 /// Renders a naming-scheme expression against a set of binding values.
 /// This is the Tauri-facing entry point into the core format engine, used by the
@@ -28,16 +30,21 @@ fn guess_episode(filename: String) -> Option<EpisodeGuess> {
     matching::guess_episode(&filename)
 }
 
-/// Executes a batch of planned on-disk renames (same-directory rename only; conflicting
-/// targets are skipped, never overwritten - see `renamr_core::rename` for the policy).
-/// The UI is expected to have already shown the user the full old-name/new-name plan
-/// and gotten explicit confirmation before calling this - there is no undo yet.
+/// Executes a batch of planned on-disk renames (optionally moving files into
+/// subfolders - see `renamr_core::rename`; conflicting targets are always skipped,
+/// never overwritten). The UI is expected to have already shown the user the full
+/// old-path/new-path plan and gotten explicit confirmation before calling this.
 /// Runs off the main thread since real filesystem I/O shouldn't block the UI.
+///
+/// Every successfully-renamed item is recorded to the rename history log afterward
+/// (see `history::record_batch`) so it can be undone later from the History panel.
 #[tauri::command]
-async fn execute_rename(items: Vec<RenamePlanItem>) -> Vec<RenameResult> {
-    tauri::async_runtime::spawn_blocking(move || rename::execute_renames(&items))
+async fn execute_rename(app: AppHandle, items: Vec<RenamePlanItem>) -> Vec<RenameResult> {
+    let results = tauri::async_runtime::spawn_blocking(move || rename::execute_renames(&items))
         .await
-        .unwrap_or_default()
+        .unwrap_or_default();
+    history::record_batch(&app, &results);
+    results
 }
 
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
@@ -51,6 +58,8 @@ pub fn run() {
             metadata::fetch_metadata,
             settings::get_tmdb_token,
             settings::save_tmdb_token,
+            history::list_rename_history,
+            history::undo_rename_batch,
             files::pick_files,
             files::pick_folder,
             files::expand_dropped_paths,

src/components/RenamePanel.css

@@ -454,6 +454,57 @@
   font-size: 12.5px;
 }
 
+.history-batch-list {
+  gap: 6px;
+}
+
+.history-batch {
+  padding: 8px;
+  border-radius: 8px;
+  background: rgba(255, 255, 255, 0.02);
+}
+
+.history-batch-header {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 2px 4px 6px;
+}
+
+.history-batch-when {
+  flex: 1 1 auto;
+  min-width: 0;
+  font-size: 12px;
+  color: var(--text);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.history-batch-count {
+  flex: 0 0 auto;
+  font-size: 10.5px;
+  font-weight: 700;
+  color: var(--muted-text);
+  background: rgba(255, 255, 255, 0.05);
+  border-radius: 999px;
+  padding: 2px 8px;
+}
+
+.history-undo-button {
+  flex: 0 0 auto;
+  width: auto;
+  height: 26px;
+  padding: 0 12px;
+  font-size: 11.5px;
+}
+
+.history-batch-entries {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+
 .status-bar {
   position: absolute;
   left: 18px;

src/components/RenamePanel.tsx

@@ -84,6 +84,30 @@ interface FetchResult {
   outcome: FetchOutcome;
 }
 
+// Rename history / undo. Mirrors renamr-core's `history` module (serde-tagged on
+// "status" for the outcome, same convention as RenameOutcome/FetchOutcome above).
+interface HistoryEntry {
+  source: string;
+  newPath: string;
+}
+
+interface HistoryBatch {
+  id: string;
+  /// Unix epoch milliseconds - formatted client-side with `Date`.
+  timestamp: number;
+  entries: HistoryEntry[];
+}
+
+type RevertOutcome =
+  | { status: "reverted"; restoredPath: string }
+  | { status: "skippedConflict"; existingPath: string }
+  | { status: "failed"; error: string };
+
+interface RevertResult {
+  source: string;
+  outcome: RevertOutcome;
+}
+
 function fileNameFromPath(path: string): string {
   const parts = path.split(/[\\/]/);
   return parts[parts.length - 1] ?? path;
@@ -252,6 +276,11 @@ export default function RenamePanel() {
   const [tmdbTokenInput, setTmdbTokenInput] = useState("");
   const [savingSettings, setSavingSettings] = useState(false);
   const [fetching, setFetching] = useState(false);
+  // Rename history / undo. `null` batches = not loaded yet (also used to show a
+  // loading state the first time the History panel is opened).
+  const [historyOpen, setHistoryOpen] = useState(false);
+  const [historyBatches, setHistoryBatches] = useState<HistoryBatch[] | null>(null);
+  const [undoingBatchId, setUndoingBatchId] = useState<string | null>(null);
 
   useEffect(() => {
     invoke<string | null>("get_tmdb_token")
@@ -544,6 +573,76 @@ export default function RenamePanel() {
     setRenamePlan(null);
   };
 
+  // Rename history / undo - Renamr's only safety net beyond the confirm-before-execute
+  // step, since a filesystem rename has no OS-level undo. `execute_rename` records a
+  // batch of every successfully-renamed file after each Rename; this panel lists those
+  // batches and can revert one back to its original paths.
+  const openHistory = () => {
+    setHistoryOpen(true);
+    invoke<HistoryBatch[]>("list_rename_history")
+      .then(setHistoryBatches)
+      .catch((err) => {
+        setHistoryBatches([]);
+        setStatus(`Couldn't load rename history: ${err}`);
+      });
+  };
+
+  const closeHistory = () => {
+    if (undoingBatchId) return;
+    setHistoryOpen(false);
+  };
+
+  const undoBatch = async (batch: HistoryBatch) => {
+    setUndoingBatchId(batch.id);
+    try {
+      const results = await invoke<RevertResult[]>("undo_rename_batch", { batchId: batch.id });
+      // Compute counts from `results` directly, not inside the setItems updater below -
+      // same rule as runMatching/confirmRename/runFetch above (React doesn't run a
+      // functional updater synchronously, so a counter mutated in there wouldn't be
+      // ready yet when building the status message right after).
+      const bySource = new Map(results.map((r) => [r.source, r] as const));
+      const reverted = results.filter((r) => r.outcome.status === "reverted").length;
+      const skipped = results.filter((r) => r.outcome.status === "skippedConflict").length;
+      const failed = results.filter((r) => r.outcome.status === "failed").length;
+
+      // Reconcile any currently-loaded item that was part of this batch back to its
+      // pre-rename path/filename - mirrors confirmRename's post-rename reconciliation.
+      setItems((prev) =>
+        prev.map((item) => {
+          const result = bySource.get(item.id);
+          if (!result || result.outcome.status !== "reverted") return item;
+          const restoredFileName = fileNameFromPath(result.outcome.restoredPath);
+          const [base, ext] = splitExt(restoredFileName);
+          return {
+            ...item,
+            id: result.outcome.restoredPath,
+            originalName: restoredFileName,
+            ext,
+            bindings: item.bindings ? { ...item.bindings, name: base, ext } : item.bindings,
+          };
+        })
+      );
+      setSelected((prevSelected) => {
+        if (!prevSelected) return prevSelected;
+        const result = bySource.get(prevSelected);
+        return result?.outcome.status === "reverted" ? result.outcome.restoredPath : prevSelected;
+      });
+
+      setHistoryBatches((prev) => (prev ? prev.filter((b) => b.id !== batch.id) : prev));
+
+      const parts = [`Reverted ${reverted} file${reverted === 1 ? "" : "s"}`];
+      if (skipped > 0) parts.push(`${skipped} skipped (something else is there now)`);
+      if (failed > 0) parts.push(`${failed} failed`);
+      setStatus(parts.join(", ") + ".");
+    } catch (err) {
+      setStatus(`Undo failed: ${err}`);
+    } finally {
+      setUndoingBatchId(null);
+      window.clearTimeout((undoBatch as any)._t);
+      (undoBatch as any)._t = window.setTimeout(() => setStatus(null), 5000);
+    }
+  };
+
   const openSettings = () => {
     setTmdbTokenInput("");
     setSettingsOpen(true);
@@ -727,7 +826,7 @@ export default function RenamePanel() {
               <span className="list-button-gap" />
               <ListButton icon={<RemoveIcon />} label="Exclude Selected" onClick={removeSelected} />
               <ListButton icon={<ClearIcon />} label="Clear" onClick={clearAll} />
-              <ListButton icon={<HistoryIcon />} label="History" onClick={() => notImplemented("Rename history")} />
+              <ListButton icon={<HistoryIcon />} label="History" onClick={openHistory} />
               <ListButton icon={<PresetsIcon />} label="Presets" onClick={() => notImplemented("Presets")} />
             </>
           }
@@ -906,6 +1005,62 @@ export default function RenamePanel() {
           </div>
         </div>
       )}
+
+      {historyOpen && (
+        <div className="modal-overlay" onClick={closeHistory}>
+          <div className="modal-card" onClick={(e) => e.stopPropagation()}>
+            <h2 className="modal-title">Rename History</h2>
+            <p className="modal-subtitle">
+              Every completed rename is logged here so it can be undone. Undoing moves each file back to its
+              original path — if something else now exists there, that one file is skipped rather than overwritten.
+              The log keeps the most recent 50 rename operations.
+            </p>
+            {historyBatches === null ? (
+              <p className="modal-note">Loading…</p>
+            ) : historyBatches.length === 0 ? (
+              <p className="modal-note">No renames yet — this fills in after you use Rename.</p>
+            ) : (
+              <div className="modal-plan-list history-batch-list">
+                {historyBatches.map((batch) => (
+                  <div className="history-batch" key={batch.id}>
+                    <div className="history-batch-header">
+                      <span className="history-batch-when">{new Date(batch.timestamp).toLocaleString()}</span>
+                      <span className="history-batch-count">
+                        {batch.entries.length} file{batch.entries.length === 1 ? "" : "s"}
+                      </span>
+                      <button
+                        className="action-button history-undo-button"
+                        onClick={() => undoBatch(batch)}
+                        disabled={undoingBatchId !== null}
+                      >
+                        {undoingBatchId === batch.id ? "Undoing…" : "Undo"}
+                      </button>
+                    </div>
+                    <div className="history-batch-entries">
+                      {batch.entries.map((entry, i) => (
+                        <div className="modal-plan-row" key={i}>
+                          <span className="modal-plan-old" title={entry.newPath}>
+                            {fileNameFromPath(entry.newPath)}
+                          </span>
+                          <span className="modal-plan-arrow">→</span>
+                          <span className="modal-plan-new" title={entry.source}>
+                            {fileNameFromPath(entry.source)}
+                          </span>
+                        </div>
+                      ))}
+                    </div>
+                  </div>
+                ))}
+              </div>
+            )}
+            <div className="modal-actions">
+              <button className="action-button" onClick={closeHistory} disabled={undoingBatchId !== null}>
+                Close
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
     </div>
   );
 }