build: live view for source builds, pin LC_ALL for the pipeline

Route 'pkh build' through the DebUi capture machinery 'pkh deb'
already uses instead of letting dpkg-source inherit the terminal:

- pin LANG=C and LC_ALL=C so dpkg-source emits deterministic English
  diagnostics regardless of the session locale;
- new DpkgSourceClassifier rewrites info:/warning:/error: lines into
  colored pane entries, telling benign tar warnings from failures;
- DebUi generalizes for reuse (arbitrary phase labels, build-specific
  log naming); run_source_build() drives phases and pipes subprocess
  output through the sink when a UI is present;
- glyph-free house-style summaries: 'Built in Ns:' plus artifact
  paths relative to cwd; failures print captured errors + log path;
- drop/capitalize pipeline chatter, add 'pkh build --verbose' to
  bypass the view like 'pkh deb --verbose'.

src/ui/deb.rs

@@ -1,6 +1,6 @@
-//! Live UI for `pkh deb`: a status bar with the current build phase on top
-//! and a rolling pane of rewritten log lines below ("a terminal in the
-//! terminal").
+//! Live build view (`pkh deb`, `pkh build`): a status bar with the current
+//! build phase on top and a rolling pane of rewritten log lines below
+//! ("a terminal in the terminal").
 //!
 //! Subprocess output is captured through a [`LineSink`] implementation,
 //! rewritten by classifiers ([`crate::ui::logfmt`]) and rendered in place
@@ -127,7 +127,7 @@ struct Shared {
     started: Instant,
 }
 
-/// Live build view for `pkh deb`
+/// Live build view for `pkh deb` / `pkh build`
 ///
 /// Create one per build (disabled automatically when stdout is not a TTY or
 /// when the user requests verbose output), pass it down as
@@ -202,20 +202,35 @@ impl DebUi {
         ui
     }
 
-    /// Identify the package being built; names the log file and the status bar
+    /// Identify the binary package being built; names the log file and the
+    /// status bar
     pub fn set_target(&self, package: &str, version: &str, series: &str, arch: &str) {
         if self.shared.enabled {
             self.shared.top.set_prefix(format!(
                 "Building {package} ({version}) for {series}/{arch}"
             ));
         }
+        self.open_log("deb", package, version, &format!("for {series}/{arch}"));
+    }
 
-        // Rename the log file to include the package identity (best-effort),
-        // then open it so subsequent captured lines are tee'd.
+    /// Identify the source package being built; names the log file
+    /// (`build-<package>-<version>-<timestamp>.log`) and the status bar
+    pub fn set_build_target(&self, package: &str, version: &str, distribution: &str) {
+        if self.shared.enabled {
+            self.shared.top.set_prefix(format!(
+                "Building source package {package} ({version}) for {distribution}"
+            ));
+        }
+        self.open_log("build", package, version, &format!("for {distribution}"));
+    }
+
+    /// Rename the placeholder log file to include the build identity
+    /// (best-effort), then open it so subsequent captured lines are tee'd
+    fn open_log(&self, kind: &str, package: &str, version: &str, detail: &str) {
         let old_path = self.shared.log_path.lock().unwrap().clone();
         let log_path = match old_path.parent() {
             Some(dir) => dir.join(format!(
-                "deb-{package}-{version}-{}.log",
+                "{kind}-{package}-{version}-{}.log",
                 self.shared.timestamp
             )),
             None => old_path.clone(),
@@ -231,11 +246,7 @@ impl DebUi {
             Ok(mut file) => {
                 let _ = writeln!(
                     file,
-                    "# pkh deb {} ({}) for {}/{} started {}",
-                    package,
-                    version,
-                    series,
-                    arch,
+                    "# pkh {kind} {package} ({version}) {detail} started {}",
                     chrono::Utc::now().to_rfc3339()
                 );
                 *self.shared.tee.lock().unwrap() = Some(file);
@@ -252,12 +263,18 @@ impl DebUi {
 
     /// Switch to a phase, installing its default classifier
     pub fn phase(&self, phase: Phase) {
-        self.phase_with(phase, default_classifier(phase));
+        self.phase_custom(phase.label(), default_classifier(phase));
     }
 
     /// Switch to a phase with a custom classifier (e.g. quilt with a known
     /// patch count)
     pub fn phase_with(&self, phase: Phase, classifier: Box<dyn Classifier>) {
+        self.phase_custom(phase.label(), classifier);
+    }
+
+    /// Switch to an arbitrary status label with a custom classifier; used by
+    /// flows whose phases are not part of [`Phase`] (e.g. source builds)
+    pub fn phase_custom(&self, label: &str, classifier: Box<dyn Classifier>) {
         {
             let mut st = self.shared.state.lock().unwrap();
             st.classifier = classifier;
@@ -267,7 +284,7 @@ impl DebUi {
         }
         if self.shared.enabled {
             self.shared.top.set_style(spinner_style());
-            self.shared.top.set_message(phase.label());
+            self.shared.top.set_message(label.to_string());
             self.shared.pane.set_message("");
         }
     }
@@ -299,6 +316,12 @@ impl DebUi {
         self.shared.enabled && !self.shared.suspended.load(Ordering::SeqCst)
     }
 
+    /// Whether the widget renders at all (false on non-TTY stdout); callers
+    /// use this to fall back to plain-line summaries
+    pub fn is_enabled(&self) -> bool {
+        self.shared.enabled
+    }
+
     /// Obtain a sink feeding this view; pass it to `ContextCommand::capture`
     pub fn sink(self: &Arc<Self>) -> Arc<dyn LineSink> {
         Arc::new(Sink {
@@ -325,14 +348,15 @@ impl DebUi {
         self.shared.pane.finish_and_clear();
     }
 
-    /// Clear the widget and print a success summary with the artifacts
+    /// Clear the widget and print a success summary with the artifacts,
+    /// rendered relative to the working directory when possible
     pub fn finish_success(&self, artifacts: &[PathBuf], elapsed: Duration) {
         self.suspend();
         if self.shared.enabled && !artifacts.is_empty() {
+            println!("Built in {}s:", elapsed.as_secs());
             for artifact in artifacts {
-                println!("  → {}", artifact.display());
+                println!("  {}", crate::ui::display_path(artifact));
             }
-            println!("  ✔ Built in {}s", elapsed.as_secs());
         }
     }
 
@@ -494,12 +518,13 @@ fn is_stdout_tty() -> bool {
     unsafe { libc::isatty(libc::STDOUT_FILENO) == 1 }
 }
 
-/// Default log file path for a given timestamp
+/// Default (placeholder) log file path for a given timestamp; renamed by
+/// [`DebUi::set_target`] / [`DebUi::set_build_target`] once the target is known
 fn default_log_path(timestamp: &str) -> PathBuf {
     let dir = ProjectDirs::from("com", "pkh", "pkh")
         .map(|dirs| dirs.cache_dir().join("logs"))
         .unwrap_or_else(std::env::temp_dir);
-    dir.join(format!("deb-{timestamp}.log"))
+    dir.join(format!("pkh-{timestamp}.log"))
 }
 
 static SIGINT_LOG_PATH: Mutex<Option<PathBuf>> = Mutex::new(None);

src/ui/logfmt.rs

@@ -282,6 +282,54 @@ impl Classifier for MakeClassifier {
     }
 }
 
+/// Classifier for `dpkg-source` output (source-build phases)
+///
+/// The build pipeline pins `LC_ALL=C`, so dpkg-source emits stable English
+/// messages prefixed with `info:` / `warning:` / `error:`; the prefix is
+/// stripped and the severity drives the pane color. Raw `tar:` diagnostics
+/// emitted while repacking tarballs are surfaced too.
+#[derive(Default)]
+pub struct DpkgSourceClassifier {}
+
+impl DpkgSourceClassifier {
+    /// Create a new classifier
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+impl Classifier for DpkgSourceClassifier {
+    fn feed(&mut self, _stream: Stream, line: &str) -> Vec<Action> {
+        const PREFIX: &str = "dpkg-source: ";
+        let rest = line.strip_prefix(PREFIX).unwrap_or(line);
+
+        if let Some(rest) = rest.strip_prefix("info: ") {
+            vec![Action::Shown(truncate(rest))]
+        } else if let Some(rest) = rest.strip_prefix("warning: ") {
+            vec![Action::Warning(truncate(rest))]
+        } else if let Some(rest) = rest.strip_prefix("error: ") {
+            vec![Action::Error(truncate(rest))]
+        } else if let Some(tar) = rest.strip_prefix("tar: ") {
+            // Diagnostics from the tarball repacking subprocess; warnings
+            // about unknown header keywords are benign, real failures are not.
+            let lower = tar.to_lowercase();
+            if ["error", "cannot", "failed", "exited"]
+                .iter()
+                .any(|m| lower.contains(m))
+            {
+                vec![Action::Error(truncate(tar))]
+            } else {
+                vec![Action::Warning(truncate(tar))]
+            }
+        } else if line == PREFIX.trim_end() || rest.is_empty() {
+            vec![Action::Hidden]
+        } else {
+            // Unprefixed output from a foreign subprocess: keep it visible
+            vec![Action::Shown(truncate(line))]
+        }
+    }
+}
+
 /// Classifier for `mmdebstrap` output (chroot tarball creation)
 ///
 /// mmdebstrap prefixes its own messages with `I:` / `W:` / `E:`; everything
@@ -499,6 +547,88 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_dpkg_source_severity_prefixes() {
+        let mut c = DpkgSourceClassifier::new();
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "dpkg-source: info: using patch list from debian/patches/series"
+            ),
+            vec![Action::Shown(
+                "using patch list from debian/patches/series".to_string()
+            )]
+        );
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "dpkg-source: info: applying patch debian/patches/reproducible.patch"
+            ),
+            vec![Action::Shown(
+                "applying patch debian/patches/reproducible.patch".to_string()
+            )]
+        );
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "dpkg-source: info: building hello in ../hello_2.10-5.dsc"
+            ),
+            vec![Action::Shown(
+                "building hello in ../hello_2.10-5.dsc".to_string()
+            )]
+        );
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "dpkg-source: warning: upstream signing key but no upstream signature"
+            ),
+            vec![Action::Warning(
+                "upstream signing key but no upstream signature".to_string()
+            )]
+        );
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "dpkg-source: error: unrepresentable changes to source"
+            ),
+            vec![Action::Error(
+                "unrepresentable changes to source".to_string()
+            )]
+        );
+    }
+
+    #[test]
+    fn test_dpkg_source_tar_and_unknown_lines() {
+        let mut c = DpkgSourceClassifier::new();
+        // Benign tar header-keyword warnings stay yellow
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "tar: Ignoring unknown extended header keyword 'SCHILY.xattr.user.foo'"
+            ),
+            vec![Action::Warning(
+                "Ignoring unknown extended header keyword 'SCHILY.xattr.user.foo'".to_string()
+            )]
+        );
+        // Real tar failures are errors
+        assert_eq!(
+            feed_one(
+                &mut c,
+                "tar: ../hello_2.10.orig.tar.xz: Cannot open: No such file or directory"
+            ),
+            vec![Action::Error(
+                "../hello_2.10.orig.tar.xz: Cannot open: No such file or directory".to_string()
+            )]
+        );
+        // Unprefixed foreign output stays visible
+        assert_eq!(
+            feed_one(&mut c, "gpgv: Signature made Tue 01 Jan 2026"),
+            vec![Action::Shown(
+                "gpgv: Signature made Tue 01 Jan 2026".to_string()
+            )]
+        );
+    }
+
     #[test]
     fn test_truncate_long_lines() {
         let long = "x".repeat(300);