feat(context): detect import/use statement changes in diff

Add IMPORTS CHANGED: section to the LLM prompt showing added/removed
import lines. Supports Rust use, JS/TS/Python import, Node require,
and C/C++ #include. Capped at 10 entries.

Author: Sephyi

src/domain/context.rs

@@ -36,6 +36,9 @@ pub struct PromptContext {
     /// Cross-symbol relationships detected from diff content.
     /// e.g., "validate calls parse() — both changed"
     pub connections: Vec<String>,
+    /// Import/use statement changes detected from diff.
+    /// e.g., "analyzer: added use crate::domain::DiffHunk"
+    pub import_changes: Vec<String>,
 }
 
 impl PromptContext {
@@ -58,6 +61,19 @@ impl PromptContext {
             )
         };
 
+        let imports_section = if self.import_changes.is_empty() {
+            String::new()
+        } else {
+            format!(
+                "\nIMPORTS CHANGED:\n{}\n",
+                self.import_changes
+                    .iter()
+                    .map(|i| format!("  {}", i))
+                    .collect::<Vec<_>>()
+                    .join("\n")
+            )
+        };
+
         // Calculate available chars for subject after type(scope)[!]: prefix
         let prefix_len = self.suggested_type.as_str().len()
             + self
@@ -123,7 +139,7 @@ impl PromptContext {
 SUMMARY: {summary}
 FILES: {files}
 SUGGESTED TYPE: {commit_type}{scope}
-{group_rationale}{evidence}{primary_change}{symbols}{connections}
+{group_rationale}{evidence}{primary_change}{symbols}{connections}{imports}
 DIFF:
 {diff}
 {constraints}{breaking}{metadata_breaking}{locale}{focus}{history}
@@ -143,6 +159,7 @@ Respond with ONLY this JSON:
             evidence = evidence_section,
             symbols = symbols_section,
             connections = connections_section,
+            imports = imports_section,
             breaking = breaking_warning,
             constraints = constraints_section,
             focus = focus_instruction,

src/services/context.rs

@@ -212,6 +212,7 @@ impl ContextBuilder {
             locale: config.locale.clone(),
             history_context: None, // Set by App when learn_from_history is enabled
             connections: Self::detect_connections(changes, symbols),
+            import_changes: Self::detect_import_changes(changes),
         }
     }
 
@@ -813,6 +814,49 @@ impl ContextBuilder {
         connections
     }
 
+    /// Detect added/removed import statements from diff lines.
+    fn detect_import_changes(changes: &StagedChanges) -> Vec<String> {
+        let mut imports = Vec::new();
+
+        for file in &changes.files {
+            for line in file.diff.lines() {
+                // Skip diff headers
+                if line.starts_with("+++") || line.starts_with("---") {
+                    continue;
+                }
+                // Detect added/removed import lines
+                if (line.starts_with('+') && Self::is_import_line(&line[1..]))
+                    || (line.starts_with('-') && Self::is_import_line(&line[1..]))
+                {
+                    let action = if line.starts_with('+') {
+                        "added"
+                    } else {
+                        "removed"
+                    };
+                    let stem = file
+                        .path
+                        .file_stem()
+                        .and_then(|s| s.to_str())
+                        .unwrap_or("?");
+                    let content = line[1..].trim();
+                    imports.push(format!("{}: {} {}", stem, action, content));
+                }
+            }
+        }
+
+        imports.truncate(10); // Cap to avoid prompt bloat
+        imports
+    }
+
+    fn is_import_line(line: &str) -> bool {
+        let trimmed = line.trim();
+        trimmed.starts_with("use ")
+            || trimmed.starts_with("import ")
+            || trimmed.starts_with("from ")
+            || trimmed.starts_with("require(")
+            || trimmed.starts_with("#include") // C/C++
+    }
+
     /// Scan diff content for metadata changes that indicate breaking changes.
     ///
     /// Detects: MSRV bumps, minimum engine/runtime version raises, removed features/exports.

tests/context.rs

@@ -1436,6 +1436,85 @@ fn whitespace_detection_returns_none_when_span_has_no_changes() {
     );
 }
 
+// ─── Import change detection ─────────────────────────────────────────────────
+
+#[test]
+fn detect_rust_import_changes() {
+    let changes = make_staged_changes(vec![make_file_change(
+        "src/analyzer.rs",
+        ChangeStatus::Modified,
+        "+use crate::domain::DiffHunk;\n-use crate::old_module::OldType;\n context line",
+        1,
+        1,
+    )]);
+    let ctx = ContextBuilder::build(&changes, &[], &default_config());
+    assert_eq!(ctx.import_changes.len(), 2);
+    assert!(ctx.import_changes[0].contains("added"));
+    assert!(ctx.import_changes[0].contains("use crate::domain::DiffHunk"));
+    assert!(ctx.import_changes[1].contains("removed"));
+}
+
+#[test]
+fn detect_python_import_changes() {
+    let changes = make_staged_changes(vec![make_file_change(
+        "app/main.py",
+        ChangeStatus::Modified,
+        "+from flask import Blueprint\n+import os\n",
+        2,
+        0,
+    )]);
+    let ctx = ContextBuilder::build(&changes, &[], &default_config());
+    assert_eq!(ctx.import_changes.len(), 2);
+}
+
+#[test]
+fn detect_cpp_include_changes() {
+    let changes = make_staged_changes(vec![make_file_change(
+        "src/main.cpp",
+        ChangeStatus::Modified,
+        "+#include <vector>\n-#include <list>\n",
+        1,
+        1,
+    )]);
+    let ctx = ContextBuilder::build(&changes, &[], &default_config());
+    assert_eq!(ctx.import_changes.len(), 2);
+    assert!(ctx.import_changes[0].contains("#include <vector>"));
+}
+
+#[test]
+fn import_changes_capped_at_10() {
+    let diff: String = (0..15)
+        .map(|i| format!("+use crate::mod_{i}::Type;\n"))
+        .collect();
+    let changes = make_staged_changes(vec![make_file_change(
+        "src/lib.rs",
+        ChangeStatus::Modified,
+        &diff,
+        15,
+        0,
+    )]);
+    let ctx = ContextBuilder::build(&changes, &[], &default_config());
+    assert_eq!(ctx.import_changes.len(), 10);
+}
+
+#[test]
+fn import_changes_shown_in_prompt() {
+    let changes = make_staged_changes(vec![make_file_change(
+        "src/lib.rs",
+        ChangeStatus::Modified,
+        "+use crate::new_dep::Thing;\n",
+        1,
+        0,
+    )]);
+    let ctx = ContextBuilder::build(&changes, &[], &default_config());
+    let prompt = ctx.to_prompt();
+    assert!(
+        prompt.contains("IMPORTS CHANGED:"),
+        "prompt should contain imports section"
+    );
+    assert!(prompt.contains("use crate::new_dep::Thing"));
+}
+
 // ─── Test Coverage: HARD LIMIT dedup check (#28) ─────────────────────────────
 
 #[test]