report: grow the Prompter port and move display_path out of the ui module

Prompter gains interactive(), select() and text() (with the Validator
type), and confirm() now propagates cancellation as Err so flows abort
instead of silently taking a default when the user hits Ctrl+C. The
terminal prompter implements the full port; the port also re-exports
the path display helper, which is pure presentation formatting used by
events and messages rather than terminal code.

src/build/mod.rs

@@ -170,10 +170,13 @@ fn retry_after_revendor(
     original: Box<dyn Error>,
 ) -> Result<SourceBuildOutput, Box<dyn Error>> {
     log::error!("{original}");
-    if !prompter.confirm(
-        "Re-vendor the Cargo dependencies and retry the build?",
-        false,
-    ) {
+    if !prompter
+        .confirm(
+            "Re-vendor the Cargo dependencies and retry the build?",
+            false,
+        )
+        .unwrap_or(false)
+    {
         view.finish_failure();
         return Err(original);
     }

src/main.rs

@@ -518,7 +518,7 @@ fn main() {
                     // print them as plain lines.
                     if !view.is_enabled() {
                         for artifact in output.artifacts() {
-                            println!("  {}", pkh::ui::display_path(&artifact));
+                            println!("  {}", pkh::report::display_path(&artifact));
                         }
                     }
                     if output.signed {

src/new/debian.rs

@@ -436,7 +436,7 @@ pub fn create_orig_tarball_excluding(
 
     log::info!(
         "Created orig tarball {}",
-        crate::ui::display_path(&tarball_path)
+        crate::report::display_path(&tarball_path)
     );
     Ok(tarball_path)
 }

src/new/mod.rs

@@ -251,7 +251,7 @@ fn print_success(opts: &NewOptions, outcome: &ScaffoldOutcome) {
     // `display_path` yields an empty string when the target is the cwd
     // itself (Here mode): `Created .` would be cryptic, so spell the
     // location out; the skeleton/path modes keep the `<dir>` display.
-    let display = crate::ui::display_path(&target);
+    let display = crate::report::display_path(&target);
     let location = if display.is_empty() {
         "package in the current directory".to_string()
     } else {

src/new/orig.rs

@@ -183,7 +183,7 @@ pub fn create_vendor_component(
 
     log::info!(
         "Created vendored-dependencies component {}",
-        crate::ui::display_path(&component_path)
+        crate::report::display_path(&component_path)
     );
     Ok(component_path)
 }
@@ -283,7 +283,7 @@ fn git_archive_tarball(
 
     log::info!(
         "Created orig tarball from git archive of {tag}: {}",
-        crate::ui::display_path(&dest)
+        crate::report::display_path(&dest)
     );
     Ok(dest)
 }
@@ -311,7 +311,7 @@ fn download_release(
                     Ok(path) => {
                         log::info!(
                             "Created orig tarball from the release download of {tag}: {}",
-                            crate::ui::display_path(&path)
+                            crate::report::display_path(&path)
                         );
                         Ok(path)
                     }
@@ -352,7 +352,7 @@ fn fetch_and_repack(
     log::info!(
         "Created orig tarball from {}: {}",
         source,
-        crate::ui::display_path(&dest)
+        crate::report::display_path(&dest)
     );
     Ok(dest)
 }

src/new/questions.rs

@@ -555,7 +555,7 @@ pub async fn offer_verification(
     no_verify: bool,
 ) {
     let tree = opts.target_dir(&std::env::current_dir().unwrap_or_default());
-    let display = crate::ui::display_path(&tree);
+    let display = crate::report::display_path(&tree);
     let display = if display.is_empty() {
         ".".to_string()
     } else {

src/put/mod.rs

@@ -521,7 +521,7 @@ fn discover_changes(cwd: &Path) -> Result<PathBuf, Box<dyn std::error::Error>> {
              Pass the one to upload explicitly",
             entry.source,
             many.iter()
-                .map(|p| ui::display_path(p))
+                .map(|p| crate::report::display_path(p))
                 .collect::<Vec<_>>()
                 .join(", ")
         )

src/report.rs

@@ -14,13 +14,20 @@
 //! implementations used by headless runs and tests. [`Prompter`] is
 //! deliberately blocking: an implementation may round-trip each question to
 //! a remote user, as long as it eventually answers (or takes the default).
+//! Asking can fail (the user cancels, the connection drops); flows
+//! propagate the error, which aborts them.
 
-use std::path::PathBuf;
+use std::error::Error;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 use crate::context::LineSink;
 use crate::logfmt::Classifier;
 
+/// Answer validator of [`Prompter::text`]: accepts the answer, or explains
+/// why it is rejected (the implementation re-asks with the explanation).
+pub type Validator = dyn Fn(&str) -> Result<(), String>;
+
 /// Identity of the build whose events follow, as announced through
 /// [`BuildView::target`].
 #[derive(Debug, Clone, Copy)]
@@ -94,18 +101,51 @@ pub trait BuildView: Send + Sync {
     }
 }
 
-/// Answerer of the questions a core flow may ask mid-run (confirmations
-/// now, selections and free-text input as more flows migrate).
+/// Answerer of the questions a core flow may ask mid-run.
 ///
 /// Questions are blocking on purpose: a terminal implementation waits for
 /// key presses, and a builder-server implementation may forward the question
 /// to a web client and await the answer on a channel. Implementations that
 /// cannot ask anyone answer with the question's default.
 pub trait Prompter: Send + Sync {
+    /// Whether this prompter can interact with a user at all. Flows with an
+    /// interactive and a headless path use this to pick one: a headless run
+    /// takes the defaults or fails with the list of missing answers instead
+    /// of asking question by question.
+    fn interactive(&self) -> bool {
+        false
+    }
+
     /// Ask a yes/no question. `default` is the answer to take when no user
-    /// can be reached or the question is cancelled.
-    fn confirm(&self, _question: &str, default: bool) -> bool {
-        default
+    /// can be reached; `Err` means the question was cancelled (Ctrl+C,
+    /// dropped connection) and the flow should abort.
+    fn confirm(&self, _question: &str, default: bool) -> Result<bool, Box<dyn Error>> {
+        Ok(default)
+    }
+
+    /// Ask a one-line selection among `options`, with `default`
+    /// preselected. Selector implementations may also accept typed
+    /// arbitrary text; callers validate the answer and re-ask through the
+    /// same method when they must reject one. `Err` cancels the flow.
+    fn select(
+        &self,
+        _label: &str,
+        _options: &[String],
+        default: &str,
+    ) -> Result<String, Box<dyn Error>> {
+        Ok(default.to_string())
+    }
+
+    /// Ask a free-text answer. `validate` is applied by the implementation
+    /// so invalid input re-asks at the source (mid-input for a terminal,
+    /// round-trip for a server). `Err` cancels the flow.
+    fn text(
+        &self,
+        _label: &str,
+        default: &str,
+        _validate: Option<&Validator>,
+    ) -> Result<String, Box<dyn Error>> {
+        Ok(default.to_string())
     }
 }
 
@@ -116,3 +156,24 @@ pub struct Quiet;
 
 impl BuildView for Quiet {}
 impl Prompter for Quiet {}
+
+/// Render a path for terminal display: relative to the current working
+/// directory when the target lives inside it or directly next to it
+/// (`../name`, the usual layout of build artifacts), absolute otherwise.
+///
+/// Pure formatting shared by the flows that mention paths in their events
+/// and messages; a remote frontend reproduces it (or not) on its side.
+pub fn display_path(path: &Path) -> String {
+    let Ok(cwd) = std::env::current_dir() else {
+        return path.display().to_string();
+    };
+    if let Ok(rel) = path.strip_prefix(&cwd) {
+        return rel.display().to_string();
+    }
+    if let Some(parent) = cwd.parent()
+        && let Ok(rel) = path.strip_prefix(parent)
+    {
+        return format!("../{}", rel.display());
+    }
+    path.display().to_string()
+}

src/ui.rs

@@ -10,27 +10,8 @@ pub mod prompt;
 #[cfg(test)]
 use indicatif::ProgressDrawTarget;
 use indicatif::{MultiProgress, ProgressBar, ProgressStyle};
-use std::path::Path;
 use std::time::Duration;
 
-/// Render a path for terminal display: relative to the current working
-/// directory when the target lives inside it or directly next to it
-/// (`../name`, the usual layout of build artifacts), absolute otherwise.
-pub fn display_path(path: &Path) -> String {
-    let Ok(cwd) = std::env::current_dir() else {
-        return path.display().to_string();
-    };
-    if let Ok(rel) = path.strip_prefix(&cwd) {
-        return rel.display().to_string();
-    }
-    if let Some(parent) = cwd.parent()
-        && let Ok(rel) = path.strip_prefix(parent)
-    {
-        return format!("../{}", rel.display());
-    }
-    path.display().to_string()
-}
-
 /// Style of an unsized operation: spinner and prefix on one line
 pub(crate) fn spinner_style() -> ProgressStyle {
     ProgressStyle::default_bar()

src/ui/deb.rs

@@ -232,7 +232,7 @@ impl DebUi {
         if self.shared.enabled && !artifacts.is_empty() {
             println!("Built in {}s:", elapsed.as_secs());
             for artifact in artifacts {
-                println!("  {}", crate::ui::display_path(artifact));
+                println!("  {}", crate::report::display_path(artifact));
             }
         }
     }

src/ui/prompt.rs

@@ -12,7 +12,7 @@ use crossterm::{
     style::{self, Color, Print, SetForegroundColor},
     terminal,
 };
-use std::io::{self, Write};
+use std::io::{self, IsTerminal, Write};
 use std::time::Duration;
 
 /// Why a prompt could not run interactively
@@ -32,9 +32,8 @@ impl std::fmt::Display for PromptError {
 
 impl std::error::Error for PromptError {}
 
-/// Answer validator of [`text`]: accepts the answer, or explains why it is
-/// rejected
-pub type Validator = dyn Fn(&str) -> Result<(), String>;
+/// Answer validator of [`text`] (re-exported from [`crate::report`])
+pub use crate::report::Validator;
 
 /// What a prompt's event loop asks its drawing helper to render; keeping all
 /// terminal access behind this callback makes the loops pure logic that unit
@@ -128,13 +127,37 @@ pub fn confirm(label: &str, default: bool) -> Result<bool, Box<dyn std::error::E
 }
 
 /// [`crate::report::Prompter`] answered by the interactive terminal: each
-/// question runs the matching raw-mode prompt, falling back to the default
-/// answer when no interactive terminal is attached (CI, piped input).
+/// question runs the matching raw-mode prompt. Without an interactive
+/// terminal (CI, piped input) [`Prompter::interactive`] is false — flows
+/// then take their headless path instead of asking — and a cancel (Ctrl+C)
+/// propagates as `Err` so flows can abort.
 pub struct TerminalPrompter;
 
 impl crate::report::Prompter for TerminalPrompter {
-    fn confirm(&self, question: &str, default: bool) -> bool {
-        confirm(question, default).unwrap_or(default)
+    fn interactive(&self) -> bool {
+        std::io::stdin().is_terminal() && std::io::stdout().is_terminal()
+    }
+
+    fn confirm(&self, question: &str, default: bool) -> Result<bool, Box<dyn std::error::Error>> {
+        confirm(question, default)
+    }
+
+    fn select(
+        &self,
+        label: &str,
+        options: &[String],
+        default: &str,
+    ) -> Result<String, Box<dyn std::error::Error>> {
+        select(label, options, default)
+    }
+
+    fn text(
+        &self,
+        label: &str,
+        default: &str,
+        validate: Option<&Validator>,
+    ) -> Result<String, Box<dyn std::error::Error>> {
+        text(label, default, validate)
     }
 }