refactor(depends): share execution path with prohibits via do_execute

Mirror composer's BaseDependencyCommand::doExecute by collapsing the
duplicated working-dir/load/lookup/print pipeline in depends.rs and
prohibits.rs into a single dependency::do_execute helper driven by an
`inverted` flag. The clap arg structs stay in their per-command modules
and just forward to the shared entry point.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

3 files changed, 177 insertions, 153 deletions

diff --git a/crates/mozart/src/commands/dependency.rs b/crates/mozart/src/commands/dependency.rs
index d044432..19e9430 100644
--- a/crates/mozart/src/commands/dependency.rs
+++ b/crates/mozart/src/commands/dependency.rs
@@ -6,9 +6,161 @@
 
 use indexmap::IndexSet;
 use std::collections::BTreeMap;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use anyhow::Result;
+use mozart_core::console_format;
+
+// ─────────────────────────────────────────────────────────────────────────────
+// Shared command entry point
+// ─────────────────────────────────────────────────────────────────────────────
+
+/// Inputs for [`do_execute`], collected from the `depends` / `prohibits` CLI args.
+pub struct DoExecuteArgs<'a> {
+    pub package: &'a str,
+    /// Version constraint string (only set for `prohibits`).
+    pub version: Option<&'a str>,
+    pub recursive: bool,
+    pub tree: bool,
+    pub locked: bool,
+    /// `true` for `prohibits` (why-not), `false` for `depends` (why).
+    pub inverted: bool,
+}
+
+/// Shared implementation for `depends` (why) and `prohibits` (why-not).
+///
+/// Mirrors `BaseDependencyCommand::doExecute` in Composer: a single function
+/// driven by `inverted` to switch between "who depends on X?" and
+/// "who prevents X version V from being installed?".
+pub fn do_execute(
+    cli: &super::Cli,
+    console: &mozart_core::console::Console,
+    args: DoExecuteArgs<'_>,
+) -> Result<()> {
+    let DoExecuteArgs {
+        package,
+        version,
+        recursive,
+        tree,
+        locked,
+        inverted,
+    } = args;
+
+    let working_dir = match &cli.working_dir {
+        Some(dir) => PathBuf::from(dir),
+        None => std::env::current_dir()?,
+    };
+
+    let packages = load_packages(&working_dir, locked)?;
+
+    if packages.is_empty() {
+        console.write_error(
+            "No dependencies installed. Try running mozart install or update, or use --locked.",
+        );
+        return Err(mozart_core::exit_code::bail_silent(
+            mozart_core::exit_code::GENERAL_ERROR,
+        ));
+    }
+
+    let target = package.to_lowercase();
+
+    let target_known = packages.iter().any(|p| p.name.to_lowercase() == target);
+    if !target_known {
+        if !inverted && mozart_core::platform::is_platform_package(&target) {
+            anyhow::bail!(
+                "Could not find platform package \"{}\". Is PHP available?",
+                package
+            );
+        }
+        anyhow::bail!("Could not find package \"{}\" in your project", package);
+    }
+
+    let constraint = match version {
+        Some(v) => Some(
+            mozart_semver::VersionConstraint::parse(v)
+                .map_err(|e| anyhow::anyhow!("Invalid version constraint '{}': {}", v, e))?,
+        ),
+        None => None,
+    };
+
+    let recursive = tree || recursive;
+    let needles = vec![target];
+
+    let results = get_dependents(
+        &packages,
+        &needles,
+        constraint.as_ref(),
+        inverted,
+        recursive,
+    )?;
+
+    if results.is_empty() {
+        if inverted {
+            console.write_stdout(
+                &console_format!(
+                    "<info>{} {} can be installed.</info>",
+                    package,
+                    version.unwrap_or("")
+                ),
+                mozart_core::console::Verbosity::Normal,
+            );
+            return Ok(());
+        }
+        console.info(&format!(
+            "There is no installed package depending on \"{}\"",
+            package
+        ));
+        return Err(mozart_core::exit_code::bail_silent(
+            mozart_core::exit_code::GENERAL_ERROR,
+        ));
+    }
+
+    if tree {
+        print_tree(&results, 0, console);
+    } else {
+        print_table(&results, console);
+    }
+
+    if !inverted {
+        return Ok(());
+    }
+
+    // Resolution hint: pick the right composer command based on whether the
+    // package sits in root's `require`, `require-dev`, or neither.
+    let needle_lower = package.to_lowercase();
+    let composer_command = packages
+        .iter()
+        .find(|p| p.is_root)
+        .map(|root| {
+            if root
+                .require
+                .keys()
+                .any(|k| k.to_lowercase() == needle_lower)
+            {
+                "require"
+            } else if root
+                .require_dev
+                .keys()
+                .any(|k| k.to_lowercase() == needle_lower)
+            {
+                "require --dev"
+            } else {
+                "update"
+            }
+        })
+        .unwrap_or("update");
+
+    console.info(&format!(
+        "Not finding what you were looking for? Try calling `composer {} \"{}:{}\" --dry-run` to get another view on the problem.",
+        composer_command,
+        package,
+        version.unwrap_or("")
+    ));
+
+    Err(mozart_core::exit_code::bail_silent(
+        mozart_core::exit_code::GENERAL_ERROR,
+    ))
+}
 
 // ─────────────────────────────────────────────────────────────────────────────
 // Core types
diff --git a/crates/mozart/src/commands/depends.rs b/crates/mozart/src/commands/depends.rs
index 514ce11..9324b82 100644
--- a/crates/mozart/src/commands/depends.rs
+++ b/crates/mozart/src/commands/depends.rs
@@ -1,5 +1,4 @@
 use clap::Args;
-use std::path::PathBuf;
 
 #[derive(Args)]
 pub struct DependsArgs {
@@ -24,58 +23,16 @@ pub async fn execute(
     cli: &super::Cli,
     console: &mozart_core::console::Console,
 ) -> anyhow::Result<()> {
-    let working_dir = match &cli.working_dir {
-        Some(dir) => PathBuf::from(dir),
-        None => std::env::current_dir()?,
-    };
-
-    let packages = super::dependency::load_packages(&working_dir, args.locked)?;
-
-    if packages.is_empty() {
-        console.write_error(
-            "No dependencies installed. Try running mozart install or update, or use --locked.",
-        );
-        return Err(mozart_core::exit_code::bail_silent(
-            mozart_core::exit_code::GENERAL_ERROR,
-        ));
-    }
-
-    let target = args.package.to_lowercase();
-
-    // Verify the target package is known
-    let target_known = packages.iter().any(|p| p.name.to_lowercase() == target);
-    if !target_known && mozart_core::platform::is_platform_package(&target) {
-        anyhow::bail!(
-            "Could not find platform package \"{}\". Is PHP available?",
-            args.package
-        );
-    }
-    if !target_known {
-        anyhow::bail!(
-            "Could not find package \"{}\" in your project",
-            args.package
-        );
-    }
-
-    let recursive = args.tree || args.recursive;
-    let needles = vec![target];
-    let results = super::dependency::get_dependents(&packages, &needles, None, false, recursive)?;
-
-    if results.is_empty() {
-        console.info(&format!(
-            "There is no installed package depending on \"{}\"",
-            args.package
-        ));
-        return Err(mozart_core::exit_code::bail_silent(
-            mozart_core::exit_code::GENERAL_ERROR,
-        ));
-    }
-
-    if args.tree {
-        super::dependency::print_tree(&results, 0, console);
-    } else {
-        super::dependency::print_table(&results, console);
-    }
-
-    Ok(())
+    super::dependency::do_execute(
+        cli,
+        console,
+        super::dependency::DoExecuteArgs {
+            package: &args.package,
+            version: None,
+            recursive: args.recursive,
+            tree: args.tree,
+            locked: args.locked,
+            inverted: false,
+        },
+    )
 }
diff --git a/crates/mozart/src/commands/prohibits.rs b/crates/mozart/src/commands/prohibits.rs
index 8eb4166..4bb00e4 100644
--- a/crates/mozart/src/commands/prohibits.rs
+++ b/crates/mozart/src/commands/prohibits.rs
@@ -1,6 +1,4 @@
 use clap::Args;
-use mozart_core::console_format;
-use std::path::PathBuf;
 
 #[derive(Args)]
 pub struct ProhibitsArgs {
@@ -28,99 +26,16 @@ pub async fn execute(
     cli: &super::Cli,
     console: &mozart_core::console::Console,
 ) -> anyhow::Result<()> {
-    let working_dir = match &cli.working_dir {
-        Some(dir) => PathBuf::from(dir),
-        None => std::env::current_dir()?,
-    };
-
-    let packages = super::dependency::load_packages(&working_dir, args.locked)?;
-
-    if packages.is_empty() {
-        console.write_error(
-            "No dependencies installed. Try running mozart install or update, or use --locked.",
-        );
-        return Err(mozart_core::exit_code::bail_silent(
-            mozart_core::exit_code::GENERAL_ERROR,
-        ));
-    }
-
-    let target = args.package.to_lowercase();
-
-    // Fix #2: Verify the target package is known
-    let target_known = packages.iter().any(|p| p.name.to_lowercase() == target);
-    if !target_known {
-        anyhow::bail!(
-            "Could not find package \"{}\" in your project",
-            args.package
-        );
-    }
-
-    // Parse the version constraint the user is asking about
-    let version_constraint = mozart_semver::VersionConstraint::parse(&args.version)
-        .map_err(|e| anyhow::anyhow!("Invalid version constraint '{}': {}", args.version, e))?;
-
-    let recursive = args.tree || args.recursive;
-    let needles = vec![target];
-
-    let results = super::dependency::get_dependents(
-        &packages,
-        &needles,
-        Some(&version_constraint),
-        true, // inverted = prohibits mode
-        recursive,
-    )?;
-
-    if results.is_empty() {
-        console.write_stdout(
-            &console_format!(
-                "<info>{} {} can be installed.</info>",
-                args.package,
-                args.version
-            ),
-            mozart_core::console::Verbosity::Normal,
-        );
-        return Ok(());
-    }
-
-    if args.tree {
-        super::dependency::print_tree(&results, 0, console);
-    } else {
-        super::dependency::print_table(&results, console);
-    }
-
-    // Fix #5: Print resolution hint message
-    // Determine the appropriate composer command based on whether the needle
-    // is in root's require or require-dev.
-    let needle_lower = args.package.to_lowercase();
-    let composer_command = packages
-        .iter()
-        .find(|p| p.is_root)
-        .map(|root| {
-            if root
-                .require
-                .keys()
-                .any(|k| k.to_lowercase() == needle_lower)
-            {
-                "require"
-            } else if root
-                .require_dev
-                .keys()
-                .any(|k| k.to_lowercase() == needle_lower)
-            {
-                "require --dev"
-            } else {
-                "update"
-            }
-        })
-        .unwrap_or("update");
-
-    console.info(&format!(
-        "Not finding what you were looking for? Try calling `composer {} \"{}:{}\" --dry-run` to get another view on the problem.",
-        composer_command, args.package, args.version
-    ));
-
-    // Fix #3: Return exit code 1 when prohibitors are found
-    Err(mozart_core::exit_code::bail_silent(
-        mozart_core::exit_code::GENERAL_ERROR,
-    ))
+    super::dependency::do_execute(
+        cli,
+        console,
+        super::dependency::DoExecuteArgs {
+            package: &args.package,
+            version: Some(&args.version),
+            recursive: args.recursive,
+            tree: args.tree,
+            locked: args.locked,
+            inverted: true,
+        },
+    )
 }