refactor(io): model ask_and_validate validators with anyhow::Result

PHP's askAndValidate throws when a validator rejects input. Change the
IOInterface validator callback and return type to anyhow::Result so the
call sites can return Err instead of panic, faithfully modeling the throw
semantics already supported by the Question layer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

4 files changed, 14 insertions, 17 deletions

diff --git a/crates/shirabe/src/io/buffer_io.rs b/crates/shirabe/src/io/buffer_io.rs
index 291b64b..836fd95 100644
--- a/crates/shirabe/src/io/buffer_io.rs
+++ b/crates/shirabe/src/io/buffer_io.rs
@@ -175,10 +175,10 @@ impl crate::io::IOInterfaceImmutable for BufferIO {
     fn ask_and_validate(
         &self,
         question: String,
-        validator: Box<dyn Fn(PhpMixed) -> PhpMixed>,
+        validator: Box<dyn Fn(PhpMixed) -> anyhow::Result<PhpMixed>>,
         attempts: Option<i64>,
         default: PhpMixed,
-    ) -> PhpMixed {
+    ) -> anyhow::Result<PhpMixed> {
         self.inner
             .ask_and_validate(question, validator, attempts, default)
     }
diff --git a/crates/shirabe/src/io/console_io.rs b/crates/shirabe/src/io/console_io.rs
index b69b68b..44e5609 100644
--- a/crates/shirabe/src/io/console_io.rs
+++ b/crates/shirabe/src/io/console_io.rs
@@ -487,10 +487,10 @@ impl IOInterfaceImmutable for ConsoleIO {
     fn ask_and_validate(
         &self,
         question: String,
-        validator: Box<dyn Fn(PhpMixed) -> PhpMixed>,
+        validator: Box<dyn Fn(PhpMixed) -> anyhow::Result<PhpMixed>>,
         attempts: Option<i64>,
         default: PhpMixed,
-    ) -> PhpMixed {
+    ) -> anyhow::Result<PhpMixed> {
         let _helper = self.helper_set.get("question");
         let sanitized_question = Self::sanitize(PhpMixed::String(question), true)
             .as_string()
@@ -502,13 +502,10 @@ impl IOInterfaceImmutable for ConsoleIO {
             Some(default)
         };
         let mut question = Question::new(&sanitized_question, sanitized_default);
-        // TODO(phase-b): IOInterface validator type is Box<dyn Fn(PhpMixed) -> PhpMixed>
-        // but Question::set_validator expects Option<Box<dyn Fn(Option<PhpMixed>) -> Result<PhpMixed>>>.
-        // Bridge the signatures by adapting the input/output types.
+        // Question::set_validator takes Fn(Option<PhpMixed>) -> Result<PhpMixed>; adapt the
+        // None answer to PHP's null and forward the validator's Result unchanged.
         let adapted: Box<dyn Fn(Option<PhpMixed>) -> anyhow::Result<PhpMixed>> =
-            Box::new(move |answer: Option<PhpMixed>| {
-                Ok(validator(answer.unwrap_or(PhpMixed::Null)))
-            });
+            Box::new(move |answer: Option<PhpMixed>| validator(answer.unwrap_or(PhpMixed::Null)));
         question.set_validator(Some(adapted));
         question.set_max_attempts(attempts);
 
diff --git a/crates/shirabe/src/io/io_interface.rs b/crates/shirabe/src/io/io_interface.rs
index e48f9ce..e33cea2 100644
--- a/crates/shirabe/src/io/io_interface.rs
+++ b/crates/shirabe/src/io/io_interface.rs
@@ -101,10 +101,10 @@ pub trait IOInterfaceImmutable: std::fmt::Debug {
     fn ask_and_validate(
         &self,
         question: String,
-        validator: Box<dyn Fn(PhpMixed) -> PhpMixed>,
+        validator: Box<dyn Fn(PhpMixed) -> anyhow::Result<PhpMixed>>,
         attempts: Option<i64>,
         default: PhpMixed,
-    ) -> PhpMixed;
+    ) -> anyhow::Result<PhpMixed>;
 
     fn ask_and_hide_answer(&self, question: String) -> Option<String>;
 
@@ -279,10 +279,10 @@ impl IOInterfaceImmutable for Rc<RefCell<dyn IOInterface>> {
     fn ask_and_validate(
         &self,
         question: String,
-        validator: Box<dyn Fn(PhpMixed) -> PhpMixed>,
+        validator: Box<dyn Fn(PhpMixed) -> anyhow::Result<PhpMixed>>,
         attempts: Option<i64>,
         default: PhpMixed,
-    ) -> PhpMixed {
+    ) -> anyhow::Result<PhpMixed> {
         self.borrow()
             .ask_and_validate(question, validator, attempts, default)
     }
diff --git a/crates/shirabe/src/io/null_io.rs b/crates/shirabe/src/io/null_io.rs
index 85a5fa5..0a83bff 100644
--- a/crates/shirabe/src/io/null_io.rs
+++ b/crates/shirabe/src/io/null_io.rs
@@ -70,11 +70,11 @@ impl IOInterfaceImmutable for NullIO {
     fn ask_and_validate(
         &self,
         _question: String,
-        _validator: Box<dyn Fn(PhpMixed) -> PhpMixed>,
+        _validator: Box<dyn Fn(PhpMixed) -> anyhow::Result<PhpMixed>>,
         _attempts: Option<i64>,
         default: PhpMixed,
-    ) -> PhpMixed {
-        default
+    ) -> anyhow::Result<PhpMixed> {
+        Ok(default)
     }
 
     fn ask_and_hide_answer(&self, _question: String) -> Option<String> {