mirror: true overall progress via --check-first + visible scan phase

With SFTP remotes rclone lists the tree while transferring, so the
`Transferred:` total grows during the run: the first ticks showed a
single file's percentage (e.g. 2.9 MiB / 8.6 MiB, 35%) which then
collapsed to 0% once the real 113 GiB total appeared. That is what
looked like "progress per album".

- pass --check-first: rclone finishes the remote listing before any
  transfer starts, so the byte total is final and the gauge is a true
  overall percentage for the whole mirror
- while scanning, no bytes move yet, so the panel now shows
  `Scanning remote · 11,810 items listed` and `0 B / 113 GiB to transfer`
  (parsed from rclone's `Checks: … Listed N`) instead of a bogus 0% bar
- once transfers start the display switches back to percentage +
  bytes + current file

Verified against the real storagebox remote (capped with
RCLONE_MAX_TRANSFER): scan ticks show listed counts climbing to 11,810
with the pending total, then transfers show `9.984 MiB / 113.477 GiB`
with the final denominator and no per-file percentage jumps.

Bump to 0.3.2.

Cargo.lock

@@ -253,7 +253,7 @@ dependencies = [
 
 [[package]]
 name = "dap-tui"
-version = "0.3.1"
+version = "0.3.2"
 dependencies = [
  "anyhow",
  "chrono",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dap-tui"
-version = "0.3.1"
+version = "0.3.2"
 edition = "2021"
 description = "Device sync for portable players — TUI edition (ratatui)"
 license = "MIT"

README.md

@@ -87,7 +87,10 @@ Firmware types: `apple` (podkit command), `rockbox`, `android`, `sony`
 ## How the sync pipeline works
 
 1. **Mirror** — `rclone sync` (or local `rsync`) pulls the StorageBox source
-   into the local library.
+   into the local library. rclone runs with `--check-first`, so the remote
+   listing completes before transfers start: the gauge then shows a true
+   overall percentage instead of the growing-total estimate, and the listing
+   phase is displayed as `Scanning remote · N items listed`.
 2. **Diff** — the device is scanned and compared to the source with
    NFC-normalised paths, size, and 2-second-rounded mtimes (FAT32 friendly).
 3. **Sync** — stale files are removed first, then `rsync --files-from` copies

src/engine.rs

@@ -1,5 +1,5 @@
 use crate::config::{self, Config, Device, Firmware};
-use crate::progress::{parse_rclone_current, parse_rclone_stats, parse_rsync_line, RsyncLine};
+use crate::progress::{parse_rclone_current, parse_rclone_listed, parse_rclone_stats, parse_rsync_line, RsyncLine};
 use chrono::Local;
 use std::collections::HashMap;
 use std::fs;
@@ -49,6 +49,9 @@ pub struct ProgressInfo {
     pub speed: String,
     pub eta: String,
     pub current: String,
+    /// rclone only: number of remote items listed so far (during the scan
+    /// phase before `--check-first` lets transfers start).
+    pub listed: u64,
 }
 
 #[derive(Debug, Clone)]
@@ -137,6 +140,13 @@ impl WorkerCtx {
         self.changed();
     }
 
+    fn set_mirror_listed(&self, listed: u64) {
+        if let Ok(mut s) = self.state.lock() {
+            s.mirror.listed = listed;
+        }
+        self.changed();
+    }
+
     fn set_device_progress(&self, done: u64, total: u64, speed: &str, eta: &str, current: &str, pct: Option<u16>) {
         if let Ok(mut s) = self.state.lock() {
             let p = &mut s.device_prog;
@@ -420,10 +430,23 @@ fn run_mirror(config: &Config, device: &Device, ctx: &WorkerCtx) -> Result<(), S
     // multi-line `Transferred: … / …, N%, speed, ETA …` block newline-terminated,
     // so it streams live through the pipe and we can update the gauge in real
     // time while a cloud→local mirror is running.
+    //
+    // `--check-first` completes the remote listing before any transfer starts.
+    // Without it (e.g. over SFTP) rclone lists while transferring, so the
+    // `Transferred:` total keeps growing and the percentage stuck near 0% —
+    // early ticks even showed a single file's percentage, which looked like
+    // per-album progress. With the full total known up front the gauge is a
+    // true overall percentage; the initial listing shows as a scan phase.
     args.extend(
-        ["--create-empty-src-dirs", "--progress", "--stats", "1s"]
-            .iter()
-            .map(|s| s.to_string()),
+        [
+            "--create-empty-src-dirs",
+            "--check-first",
+            "--progress",
+            "--stats",
+            "1s",
+        ]
+        .iter()
+        .map(|s| s.to_string()),
     );
 
     stream(ctx, "rclone", &args, |line| {
@@ -431,6 +454,11 @@ fn run_mirror(config: &Config, device: &Device, ctx: &WorkerCtx) -> Result<(), S
             ctx.set_mirror(p);
             return true;
         }
+        // `Checks: … Listed N` — the remote scan phase before transfers start.
+        if let Some(listed) = parse_rclone_listed(line) {
+            ctx.set_mirror_listed(listed);
+            return true;
+        }
         if let Some(file) = parse_rclone_current(line) {
             // Per-file `Transferring:` entry — show it as the current file
             // instead of logging it once per second.
@@ -947,6 +975,7 @@ mod tests {
 
 
 
+
     #[cfg(unix)]
     fn process_is_alive(pid: i32) -> bool {
         match std::fs::read_to_string(format!("/proc/{pid}/stat")) {

src/progress.rs

@@ -234,6 +234,16 @@ pub fn parse_rclone_stats(line: &str) -> Option<RcloneStats> {
     })
 }
 
+/// Parse the "Listed N" counter from an rclone `Checks:` progress line:
+/// `Checks:                 0 / 0, -, Listed 11810`.
+/// rclone prints this while scanning the remote tree (before `--check-first`
+/// lets any transfer start), so it is the only progress signal in that phase.
+pub fn parse_rclone_listed(line: &str) -> Option<u64> {
+    let (_, rest) = line.trim().split_once("Listed")?;
+    let n = rest.split_whitespace().next()?;
+    n.replace(',', "").parse().ok()
+}
+
 /// A size like `80 MiB` / `0 B` — but not a plain file count like `6`.
 fn has_size_unit(s: &str) -> bool {
     s.chars().any(|c| c.is_ascii_alphabetic())
@@ -339,6 +349,20 @@ mod tests {
         assert_eq!(s.eta, "2s");
     }
 
+    #[test]
+    fn parses_rclone_listed_count() {
+        assert_eq!(
+            parse_rclone_listed("Checks:                 0 / 0, -, Listed 11810"),
+            Some(11810)
+        );
+        assert_eq!(
+            parse_rclone_listed("Checks:   5 / 10, 50%, Listed 1,234"),
+            Some(1234)
+        );
+        assert!(parse_rclone_listed("Transferred: 1 MiB / 2 MiB, 50%").is_none());
+        assert!(parse_rclone_listed("Elapsed time: 5.0s").is_none());
+    }
+
     #[test]
     fn parses_rclone_current_file() {
         assert_eq!(

src/ui/mod.rs

@@ -356,4 +356,43 @@ mod tests {
         assert!(out.contains("32.082 MiB"), "transferred bytes missing");
         assert!(out.contains("sub/file3.bin"), "current file missing");
     }
+
+    #[test]
+    fn renders_mirror_scanning_phase() {
+        use crate::engine::{StepState, StepStatus};
+
+        let mut app = test_app();
+        {
+            let mut s = app.engine.state.lock().unwrap();
+            s.running = true;
+            s.device = Some("Test Player".into());
+            s.steps = vec![
+                StepState {
+                    title: "Mirror StorageBox".into(),
+                    detail: "refreshing local library…".into(),
+                    status: StepStatus::Active,
+                },
+                StepState {
+                    title: "Sync Test Player".into(),
+                    detail: "rockbox · music".into(),
+                    status: StepStatus::Pending,
+                },
+            ];
+            // --check-first listing phase: no bytes moved, total still growing.
+            s.mirror.pct = 0;
+            s.mirror.done = "0 B".into();
+            s.mirror.total = "113.477 GiB".into();
+            s.mirror.listed = 11810;
+        }
+        app.tab = crate::app::Tab::Sync;
+
+        let out = render(&app, 100, 30);
+        assert!(out.contains("Scanning remote"), "scan label missing");
+        assert!(out.contains("11,810"), "listed count missing");
+        assert!(out.contains("113.477 GiB"), "pending total missing");
+        assert!(
+            !out.contains("Mirroring local library"),
+            "scan phase must replace the 0% mirror label"
+        );
+    }
 }

src/ui/tabs/sync.rs

@@ -258,7 +258,7 @@ fn draw_progress(f: &mut Frame, area: Rect, state: &SyncState) {
         .position(|s| s.status == StepStatus::Active)
         .unwrap_or(usize::MAX);
 
-    let (pct, done, total, speed, eta, current, label) = if active == 0 {
+    let (pct, done, total, speed, eta, current, listed, label) = if active == 0 {
         (
             state.mirror.pct,
             state.mirror.done.clone(),
@@ -266,6 +266,7 @@ fn draw_progress(f: &mut Frame, area: Rect, state: &SyncState) {
             state.mirror.speed.clone(),
             state.mirror.eta.clone(),
             state.mirror.current.clone(),
+            state.mirror.listed,
             "Mirroring local library",
         )
     } else if active == 1 {
@@ -276,20 +277,39 @@ fn draw_progress(f: &mut Frame, area: Rect, state: &SyncState) {
             state.device_prog.speed.clone(),
             state.device_prog.eta.clone(),
             state.device_prog.current.clone(),
+            0,
             "Syncing device",
         )
     } else {
-        (0, String::new(), String::new(), String::new(), String::new(), String::new(), "Finalizing")
+        (
+            0,
+            String::new(),
+            String::new(),
+            String::new(),
+            String::new(),
+            String::new(),
+            0,
+            "Finalizing",
+        )
     };
 
+    // With --check-first, rclone lists the whole remote before transferring:
+    // no bytes move yet, so show the scan instead of a meaningless 0% gauge.
+    let scanning = listed > 0 && (done.is_empty() || done == "0 B");
+
     let [gauge_row, stats] = Layout::vertical([Constraint::Length(2), Constraint::Min(0)]).areas(inner);
 
+    let gauge_label = if scanning {
+        format!(" Scanning remote  ·  {} items listed ", fmt_count(listed))
+    } else {
+        format!(" {label}  ·  {pct}% ")
+    };
     let g = Gauge::default()
         .block(Block::default().borders(Borders::BOTTOM).border_style(Style::default().fg(theme::BORDER)))
         .gauge_style(Style::default().fg(theme::ACCENT).bg(theme::BG_ALT))
         .ratio((pct as f64) / 100.0)
         .label(Span::styled(
-            format!(" {label}  ·  {pct}% "),
+            gauge_label,
             // No explicit colour: Gauge swaps fg/bg under the label so text
             // stays readable over both the filled and empty bar.
             Style::default().add_modifier(Modifier::BOLD),
@@ -309,6 +329,9 @@ fn draw_progress(f: &mut Frame, area: Rect, state: &SyncState) {
         if total.is_empty() { "…".to_string() } else { total },
         Style::default().fg(theme::CYAN),
     ));
+    if scanning {
+        left.push(Span::styled(" to transfer", Style::default().fg(theme::DIM)));
+    }
 
     let mut right: Vec<Span> = Vec::new();
     if !speed.is_empty() {
@@ -326,10 +349,15 @@ fn draw_progress(f: &mut Frame, area: Rect, state: &SyncState) {
     left.extend(right);
 
     let mut lines = vec![Line::from(left)];
+    let current_line = if scanning && current.is_empty() {
+        "building the file list…".to_string()
+    } else {
+        current.clone()
+    };
     lines.push(Line::from(vec![
         Span::raw("  "),
         Span::styled(
-            truncate(&current, inner.width.saturating_sub(2) as usize),
+            truncate(&current_line, inner.width.saturating_sub(2) as usize),
             Style::default().fg(theme::DIM),
         ),
     ]));
@@ -338,3 +366,16 @@ fn draw_progress(f: &mut Frame, area: Rect, state: &SyncState) {
         stats,
     );
 }
+
+/// `11810` → `11,810`
+fn fmt_count(n: u64) -> String {
+    let s = n.to_string();
+    let mut out = String::with_capacity(s.len() + s.len() / 3);
+    for (i, c) in s.chars().enumerate() {
+        if i > 0 && (s.len() - i) % 3 == 0 {
+            out.push(',');
+        }
+        out.push(c);
+    }
+    out
+}