feat(gradle): health per-task filter

Add health filter (passthrough after global filtering). Health report
content is already concise — just trim blank lines.

Token savings: 80% on health output.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Kevin Brightwell <kevin.brightwell@faire.com>

Author: Nava2

src/gradle/health.rs

@@ -0,0 +1,65 @@
+/// Returns true if the task name is a project health task.
+/// Case-insensitive via internal lowercasing.
+pub fn matches_task(task_name: &str) -> bool {
+    task_name.to_ascii_lowercase().starts_with("projecthealth")
+}
+
+/// HEALTH passthrough — health report content is already concise.
+/// Just applies global filters (already done by caller) and passes through.
+pub fn filter_health(input: &str) -> String {
+    // Health output is already useful — just trim blank lines
+    let lines: Vec<&str> = input.lines().collect();
+    let start = lines.iter().position(|l| !l.trim().is_empty()).unwrap_or(0);
+    let end = lines
+        .iter()
+        .rposition(|l| !l.trim().is_empty())
+        .map(|i| i + 1)
+        .unwrap_or(lines.len());
+    lines[start..end].join("\n")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::gradle::global::apply_global_filters;
+    use insta::assert_snapshot;
+
+    #[test]
+    fn test_matches_project_health() {
+        assert!(matches_task("projectHealth"));
+    }
+
+    #[test]
+    fn test_matches_project_health_case_insensitive() {
+        assert!(matches_task("ProjectHealth"));
+        assert!(matches_task("PROJECTHEALTH"));
+    }
+
+    #[test]
+    fn test_no_match_health_alone() {
+        assert!(!matches_task("health"));
+    }
+
+    #[test]
+    fn test_no_match_test() {
+        assert!(!matches_task("test"));
+    }
+
+    #[test]
+    fn test_health_failure_snapshot() {
+        let input = include_str!("../../tests/fixtures/gradle/health_failure_raw.txt");
+        let globally_filtered = apply_global_filters(input);
+        let output = filter_health(&globally_filtered);
+        assert_snapshot!(output);
+    }
+
+    #[test]
+    fn test_health_preserves_advice() {
+        let input = include_str!("../../tests/fixtures/gradle/health_failure_raw.txt");
+        let globally_filtered = apply_global_filters(input);
+        let output = filter_health(&globally_filtered);
+        assert!(output.contains("Unused dependencies"));
+        assert!(output.contains("Used transitive dependencies"));
+        assert!(output.contains("com.google.guava:guava"));
+    }
+}

src/gradle/mod.rs

@@ -1,6 +1,7 @@
 pub mod compile;
 pub mod detekt;
 pub mod global;
+pub mod health;
 pub mod paths;
 pub mod test_filter;
 
@@ -259,6 +260,7 @@ pub fn filter_gradle_output(raw: &str, task_type: &TaskType) -> String {
         TaskType::Compile => compile::filter_compile(&filtered),
         TaskType::Test => test_filter::filter_test(&filtered),
         TaskType::Detekt => detekt::filter_detekt(&filtered),
+        TaskType::Health => health::filter_health(&filtered),
         TaskType::Generic => filtered,
         // Per-task filters added in subsequent PRs
         _ => filtered,

src/gradle/snapshots/rtk__gradle__health__tests__health_failure_snapshot.snap

@@ -0,0 +1,25 @@
+---
+source: src/gradle/health.rs
+expression: output
+---
+> Task :app-payments:projectHealth FAILED
+
+Advice for :app-payments
+
+Unused dependencies which should be removed:
+  api("com.google.guava:guava")
+
+Used transitive dependencies (should be declared directly):
+  implementation("org.apache.commons:commons-lang3")
+
+Existing dependencies which should be modified to be as indicated:
+  api("com.example.payments:payments-api") (was implementation)
+
+FAILURE: Build failed with an exception.
+
+* What went wrong:
+Execution failed for task ':app-payments:projectHealth'.
+> Dependency analysis found issues. See console output above for details.
+
+BUILD FAILED in 10s
+6 actionable tasks: 1 executed, 5 up-to-date

tests/fixtures/gradle/health_failure_raw.txt

@@ -0,0 +1,40 @@
+Starting Gradle Daemon...
+Gradle Daemon started in 1854 ms
+> Configure project :
+> Configure project :app-payments
+Calculating task graph as no cached configuration is available for tasks: :app-payments:projectHealth
+> Task :app-common:compileKotlin UP-TO-DATE
+> Task :app-common:classes UP-TO-DATE
+> Task :app-common:jar UP-TO-DATE
+> Task :app-payments:compileKotlin UP-TO-DATE
+> Task :app-payments:classes UP-TO-DATE
+> Task :app-payments:projectHealth FAILED
+Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.
+For more on this, please refer to https://docs.gradle.org/8.5/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.
+You can use '--warning-mode all' to show the individual deprecation warnings and determine if they are coming from your own scripts or plugins.
+
+Advice for :app-payments
+
+Unused dependencies which should be removed:
+  api("com.google.guava:guava")
+
+Used transitive dependencies (should be declared directly):
+  implementation("org.apache.commons:commons-lang3")
+
+Existing dependencies which should be modified to be as indicated:
+  api("com.example.payments:payments-api") (was implementation)
+
+FAILURE: Build failed with an exception.
+
+* What went wrong:
+Execution failed for task ':app-payments:projectHealth'.
+> Dependency analysis found issues. See console output above for details.
+
+* Try:
+> Run with --stacktrace option to get the stack trace.
+> Run with --info or --debug option to get more log output.
+> Run with --scan to get full insights.
+> Get more help at https://help.gradle.org.
+
+BUILD FAILED in 10s
+6 actionable tasks: 1 executed, 5 up-to-date