diff --git a/crates/kebab-parse-code/src/lang.rs b/crates/kebab-parse-code/src/lang.rs
index bd850f6..1128ac7 100644
--- a/crates/kebab-parse-code/src/lang.rs
+++ b/crates/kebab-parse-code/src/lang.rs
@@ -40,3 +40,73 @@ pub fn code_lang_for_path(path: &Path) -> Option<&'static str> {
         _ => None,
     }
 }
+
+/// p10-1B: workspace-relative Python file path → dotted module-path prefix.
+/// See plan §Task C for the exact rules + tasks/p10/p10-1b for the §3.4
+/// design contract.
+pub fn module_path_for_python(workspace_path: &str) -> String {
+    let mut p: &str = workspace_path;
+    if let Some(rest) = p.strip_prefix("crates/") {
+        if let Some(slash) = rest.find('/') {
+            let after = &rest[slash + 1..];
+            if let Some(stripped) = after.strip_prefix("src/") {
+                p = stripped;
+            }
+        }
+    } else if let Some(stripped) = p.strip_prefix("src/") {
+        p = stripped;
+    } else if let Some(stripped) = p.strip_prefix("lib/") {
+        p = stripped;
+    }
+    let p = match p.strip_suffix(".py") {
+        Some(s) => s,
+        None => p.strip_suffix(".pyi").unwrap_or(p),
+    };
+    let p = if let Some(parent) = p.strip_suffix("/__init__") {
+        parent
+    } else if p == "__init__" {
+        ""
+    } else {
+        p
+    };
+    p.replace('/', ".")
+}
+
+/// p10-1B: workspace-relative TS/JS file path → path-style prefix
+/// (no slash replacement, no source-root strip). See plan §Task C.
+pub fn module_path_for_tsjs(workspace_path: &str) -> String {
+    let p = workspace_path;
+    for ext in [".tsx", ".ts", ".jsx", ".mjs", ".cjs", ".js"] {
+        if let Some(stripped) = p.strip_suffix(ext) {
+            return stripped.to_string();
+        }
+    }
+    p.to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn module_path_for_python_strips_src_roots_and_extensions() {
+        assert_eq!(module_path_for_python("kebab_eval/metrics.py"),       "kebab_eval.metrics");
+        assert_eq!(module_path_for_python("kebab_eval/__init__.py"),      "kebab_eval");
+        assert_eq!(module_path_for_python("src/foo/bar.py"),              "foo.bar");
+        assert_eq!(module_path_for_python("crates/x/src/foo/bar.py"),     "foo.bar");
+        assert_eq!(module_path_for_python("a/b/c.pyi"),                   "a.b.c");
+        assert_eq!(module_path_for_python("standalone.py"),               "standalone");
+        assert_eq!(module_path_for_python("src/__init__.py"),             "");
+    }
+
+    #[test]
+    fn module_path_for_tsjs_keeps_slashes_and_strips_ext() {
+        for ext in ["ts", "tsx", "js", "jsx", "mjs", "cjs"] {
+            let p = format!("src/search/retriever/Retriever.{ext}");
+            assert_eq!(module_path_for_tsjs(&p), "src/search/retriever/Retriever");
+        }
+        assert_eq!(module_path_for_tsjs("foo.ts"),                 "foo");
+        assert_eq!(module_path_for_tsjs("a/b/c.ts"),               "a/b/c");
+        assert_eq!(module_path_for_tsjs("packages/x/src/Foo.ts"),  "packages/x/src/Foo");
+    }
+}
diff --git a/crates/kebab-parse-code/src/lib.rs b/crates/kebab-parse-code/src/lib.rs
index d9faefb..8e954e7 100644
--- a/crates/kebab-parse-code/src/lib.rs
+++ b/crates/kebab-parse-code/src/lib.rs
@@ -18,7 +18,7 @@ pub mod repo;
 pub mod rust;
 pub mod skip;
 
-pub use lang::code_lang_for_path;
+pub use lang::{code_lang_for_path, module_path_for_python, module_path_for_tsjs};
 pub use repo::{RepoMeta, detect_repo};
 pub use rust::{PARSER_VERSION as RUST_PARSER_VERSION, RustAstExtractor};
 pub use skip::{BUILTIN_BLACKLIST, is_generated_file, is_oversized};