Add incremental warmup with cache check and auto-warmup on startup

Warmup now checks the rclone VFS cache directory before reading each file
through the FUSE mount, skipping already-cached files for fast re-runs.
Also adds WarmupConfig with configurable rules that auto-execute when
the supervisor starts (best-effort, non-blocking).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

warpgate/src/cli/warmup.rs

@@ -59,9 +59,15 @@ pub fn run(config: &Config, path: &str, newer_than: Option<&str>) -> Result<()>
     println!("Found {total} files to cache.");
 
     let mut cached = 0usize;
+    let mut skipped = 0usize;
     let mut errors = 0usize;
 
     for file in &files {
+        if is_cached(config, path, file) {
+            skipped += 1;
+            continue;
+        }
+
         let full_path = warmup_path.join(file);
         match std::fs::File::open(&full_path) {
             Ok(mut f) => {
@@ -71,7 +77,7 @@ pub fn run(config: &Config, path: &str, newer_than: Option<&str>) -> Result<()>
                     errors += 1;
                 } else {
                     cached += 1;
-                    eprint!("\r  Cached {cached}/{total}");
+                    eprint!("\r  Cached {cached}/{total} (skipped {skipped})");
                 }
             }
             Err(e) => {
@@ -82,6 +88,24 @@ pub fn run(config: &Config, path: &str, newer_than: Option<&str>) -> Result<()>
     }
 
     eprintln!();
-    println!("Warmup complete: {cached} cached, {errors} errors.");
+    println!(
+        "Warmup complete: skipped {skipped} (already cached), cached {cached}, errors {errors}."
+    );
     Ok(())
 }
+
+/// Check if a file is already in the rclone VFS cache.
+///
+/// `warmup_path` is the subdir passed to `warpgate warmup` (e.g. "Image/2026").
+/// `relative_path` is the filename from `rclone lsf` (relative to warmup_path).
+fn is_cached(config: &Config, warmup_path: &str, relative_path: &str) -> bool {
+    let cache_path = config
+        .cache
+        .dir
+        .join("vfs")
+        .join("nas")
+        .join(config.connection.remote_path.trim_start_matches('/'))
+        .join(warmup_path)
+        .join(relative_path);
+    cache_path.exists()
+}

warpgate/src/config.rs

@@ -22,6 +22,8 @@ pub struct Config {
     pub directory_cache: DirectoryCacheConfig,
     pub protocols: ProtocolsConfig,
     pub mount: MountConfig,
+    #[serde(default)]
+    pub warmup: WarmupConfig,
 }
 
 /// SFTP connection to remote NAS.
@@ -141,6 +143,35 @@ pub struct MountConfig {
     pub point: PathBuf,
 }
 
+/// Warmup configuration — auto-cache paths on startup.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WarmupConfig {
+    /// Auto-warmup on startup (default: true when rules exist).
+    #[serde(default = "default_true")]
+    pub auto: bool,
+    /// Warmup rules — paths to pre-cache.
+    #[serde(default)]
+    pub rules: Vec<WarmupRule>,
+}
+
+impl Default for WarmupConfig {
+    fn default() -> Self {
+        Self {
+            auto: true,
+            rules: Vec::new(),
+        }
+    }
+}
+
+/// A single warmup rule specifying a path to pre-cache.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WarmupRule {
+    /// Path relative to remote_path.
+    pub path: String,
+    /// Only cache files newer than this (e.g. "7d", "24h").
+    pub newer_than: Option<String>,
+}
+
 // --- Default value functions ---
 
 fn default_sftp_port() -> u16 {

warpgate/src/supervisor.rs

@@ -106,6 +106,21 @@ pub fn run(config: &Config) -> Result<()> {
     println!("Starting protocol services...");
     let mut protocols = start_protocols(config)?;
 
+    // Phase 3.5: Auto-warmup (non-blocking, best-effort)
+    if !config.warmup.rules.is_empty() && config.warmup.auto {
+        println!("Running auto-warmup...");
+        for rule in &config.warmup.rules {
+            if shutdown.load(Ordering::SeqCst) {
+                break;
+            }
+            if let Err(e) =
+                crate::cli::warmup::run(config, &rule.path, rule.newer_than.as_deref())
+            {
+                eprintln!("Warmup warning: {e}");
+            }
+        }
+    }
+
     // Phase 4: Supervision loop
     println!("Supervision active. Press Ctrl+C to stop.");
     let result = supervise(config, &mut mount_child, &mut protocols, Arc::clone(&shutdown));

warpgate/templates/config.toml.default

@@ -70,3 +70,14 @@ webdav_port = 8080
 [mount]
 # FUSE mount point (all protocols share this)
 point = "/mnt/nas-photos"
+
+[warmup]
+# Auto-warmup configured paths on startup
+auto = true
+
+# [[warmup.rules]]
+# path = "2024"
+# newer_than = "30d"
+#
+# [[warmup.rules]]
+# path = "Lightroom/Catalog"