diff --git a/crates/perry/src/commands/compile/run_pipeline.rs b/crates/perry/src/commands/compile/run_pipeline.rs
index 025bda9d30..3c7dd506a7 100644
--- a/crates/perry/src/commands/compile/run_pipeline.rs
+++ b/crates/perry/src/commands/compile/run_pipeline.rs
@@ -2440,6 +2440,120 @@ pub fn run_with_parse_cache(
                     };
                     if let Some(local) = namespace_like_local {
                         namespace_imports.push(local.clone());
+                        // Issue #6586: a namespace import of a CommonJS module
+                        // whose `module.exports` value is itself the export
+                        // (`module.exports = function equal(){}`, no
+                        // `__esModule` marker) is TypeScript's
+                        // esModuleInterop=false interop — `import * as equal
+                        // from "fast-deep-equal"` binds `equal` to the whole
+                        // `require()` result (the default export), so a DIRECT
+                        // call `equal(a, b)` is a call OF that value. ajv's
+                        // `lib/compile/resolve.ts` does exactly this for
+                        // `fast-deep-equal` and `json-schema-traverse`, and
+                        // fast-json-stringify pulls ajv in. The CJS wrap emits
+                        // the value under the module's `default` symbol, but the
+                        // namespace binding had no `import_function_prefixes`
+                        // entry, so the direct call fell through to a bare
+                        // `equal` extern and the link died with
+                        // `Undefined symbols: "_equal"`. Wire the whole-value
+                        // binding to the `default` export exactly like a Default
+                        // specifier does below (member reads `ns.foo` are keyed
+                        // per-namespace via `namespace_member_prefixes` and are
+                        // unaffected). Only genuine namespace imports of a module
+                        // that actually HAS a `default` export qualify — the
+                        // #4872 default-import-of-a-named-only-barrel case that
+                        // also lands here has no `default` and is skipped.
+                        if matches!(spec, perry_hir::ImportSpecifier::Namespace { .. }) {
+                            if let Some(default_origin_path) = all_module_exports
+                                .get(&resolved_path_str)
+                                .and_then(|exports| exports.get("default"))
+                                .cloned()
+                            {
+                                let default_prefix = compute_module_prefix(
+                                    &default_origin_path,
+                                    &ctx.project_root,
+                                );
+                                let default_suffix = all_module_export_origin_names
+                                    .get(&resolved_path_str)
+                                    .and_then(|m| m.get("default"))
+                                    .cloned()
+                                    .unwrap_or_else(|| "default".to_string());
+                                import_function_prefixes
+                                    .entry(local.clone())
+                                    .or_insert(default_prefix.clone());
+                                import_function_origin_names
+                                    .entry(local.clone())
+                                    .or_insert(default_suffix.clone());
+                                // The metadata maps are keyed by
+                                // (declaring-path, exported-name); the default
+                                // is declared at `default_origin_path` under
+                                // `default_suffix` (== "default" unless a
+                                // re-export renamed it).
+                                let key = (default_origin_path.clone(), default_suffix);
+                                // A CJS `module.exports = <expr>` becomes a
+                                // var-shaped default: a value binding emitted as
+                                // a zero-arg getter. A direct call must fetch the
+                                // closure via that getter and THEN invoke it with
+                                // the args (`js_closure_callN`), so mark the local
+                                // as an imported var — otherwise the call site
+                                // treats the getter's return value AS the call
+                                // result and `equal(1, 1)` yields the function
+                                // itself instead of `true`. Mirrors the
+                                // Default-import var classification below.
+                                if exported_var_names.contains(&key)
+                                    || exported_var_names.contains(&(
+                                        resolved_path_str.clone(),
+                                        "default".to_string(),
+                                    ))
+                                {
+                                    imported_vars.insert(local.clone());
+                                }
+                                // A non-var-shaped default — a `module.exports =
+                                // function foo(){}` static-function or a
+                                // `module.exports = class Foo{}` — is called /
+                                // instantiated through the direct
+                                // `perry_fn_<mod>__default` symbol, so it needs
+                                // the same arity / rest / synthetic-arguments /
+                                // return-type / async / class / enum metadata the
+                                // Default specifier propagates below. Without it a
+                                // rest-param default mis-bundles its trailing args
+                                // and a class default has no ImportedClass entry
+                                // (so `new ns()` can't resolve). Key everything by
+                                // the namespace LOCAL, the name the consumer's
+                                // ExternFuncRef carries.
+                                if let Some(&param_count) = exported_func_param_counts.get(&key) {
+                                    imported_param_counts.insert(local.clone(), param_count);
+                                }
+                                if exported_func_has_rest.get(&key).copied().unwrap_or(false) {
+                                    imported_has_rest.insert(local.clone());
+                                }
+                                if exported_func_synthetic_arguments.contains(&key) {
+                                    imported_synthetic_arguments.insert(local.clone());
+                                }
+                                if let Some(return_type) = exported_func_return_types.get(&key) {
+                                    imported_return_types.insert(local.clone(), return_type.clone());
+                                }
+                                if exported_async_funcs.contains(&key) {
+                                    imported_async_set.insert(local.clone());
+                                }
+                                if let Some(class) = exported_classes.get(&key) {
+                                    let class_prefix = canonical_class_source_prefix(
+                                        class,
+                                        &class_canonical_path,
+                                        &ctx.project_root,
+                                        &default_prefix,
+                                    );
+                                    imported_classes.push(imported_class_from_hir(
+                                        class,
+                                        class_prefix,
+                                        Some(local.clone()),
+                                    ));
+                                }
+                                if let Some(members) = exported_enums.get(&key) {
+                                    imported_enums.push((local.clone(), members.clone()));
+                                }
+                            }
+                        }
                         // Register all exports from the source module
                         if let Some(exports) = all_module_exports.get(&resolved_path_str) {
                             for (export_name, origin_path) in exports {
diff --git a/crates/perry/tests/issue_6586_namespace_cjs_default_import.rs b/crates/perry/tests/issue_6586_namespace_cjs_default_import.rs
new file mode 100644
index 0000000000..530f506542
--- /dev/null
+++ b/crates/perry/tests/issue_6586_namespace_cjs_default_import.rs
@@ -0,0 +1,151 @@
+//! Regression test for #6586: a namespace import of a CommonJS module whose
+//! `module.exports` value is itself the export
+//! (`module.exports = function equal(){}`) — TypeScript's
+//! `esModuleInterop=false` interop shape — must bind the namespace local to the
+//! default export so a DIRECT call of it (`equal(a, b)`) links.
+//!
+//! This is the wall that blocks `fast-json-stringify` (via `ajv`): ajv's
+//! `lib/compile/resolve.ts` does
+//!
+//! ```ts
+//! import * as equal from "fast-deep-equal"
+//! import * as traverse from "json-schema-traverse"
+//! // ...
+//! traverse(schema, {allKeys: true}, (sch) => { /* ... */ })
+//! if (!equal(sch1, sch2)) throw ambiguos(ref)
+//! ```
+//!
+//! where both deps are pure CJS `module.exports = function`. Pre-fix, the
+//! namespace binding had no `import_function_prefixes` entry, so the direct
+//! calls fell through to bare `equal` / `traverse` externs and the link died
+//! with `Undefined symbols: "_equal", "_traverse"`. A DEFAULT import of the
+//! same module (`import equal from "..."`) always linked — the fix routes the
+//! namespace whole-value binding to the module's `default` symbol the same way.
+
+use std::path::PathBuf;
+use std::process::Command;
+
+fn perry_bin() -> PathBuf {
+    PathBuf::from(env!("CARGO_BIN_EXE_perry"))
+}
+
+#[test]
+fn namespace_import_of_cjs_default_function_links_and_calls() {
+    let dir = tempfile::tempdir().expect("tempdir");
+    let root = dir.path();
+
+    std::fs::write(
+        root.join("package.json"),
+        r#"{
+  "name": "ns-cjs-default",
+  "private": true,
+  "perry": {
+    "compilePackages": ["fakeequal", "faketraverse", "fakecls"],
+    "allow": { "compilePackages": ["fakeequal", "faketraverse", "fakecls"] }
+  }
+}"#,
+    )
+    .expect("write consumer package.json");
+
+    // fast-deep-equal shape: a bare `module.exports = function`.
+    let equal_pkg = root.join("node_modules").join("fakeequal");
+    std::fs::create_dir_all(&equal_pkg).expect("mkdir fakeequal");
+    std::fs::write(
+        equal_pkg.join("package.json"),
+        r#"{ "name": "fakeequal", "version": "1.0.0", "main": "index.js" }"#,
+    )
+    .expect("write fakeequal package.json");
+    std::fs::write(
+        equal_pkg.join("index.js"),
+        "'use strict';\nmodule.exports = function equal(a, b) { return a === b; };\n",
+    )
+    .expect("write fakeequal index.js");
+
+    // json-schema-traverse shape: `module.exports = fn` PLUS a
+    // `module.exports.default = fn` self-reference (a named `default` on top of
+    // the CJS default value).
+    let traverse_pkg = root.join("node_modules").join("faketraverse");
+    std::fs::create_dir_all(&traverse_pkg).expect("mkdir faketraverse");
+    std::fs::write(
+        traverse_pkg.join("package.json"),
+        r#"{ "name": "faketraverse", "version": "1.0.0", "main": "index.js" }"#,
+    )
+    .expect("write faketraverse package.json");
+    std::fs::write(
+        traverse_pkg.join("index.js"),
+        "'use strict';\nfunction traverse(schema, cb) { cb(schema); return schema.n * 2; }\nmodule.exports = traverse;\nmodule.exports.default = traverse;\n",
+    )
+    .expect("write faketraverse index.js");
+
+    // A CJS default that is a CLASS (`module.exports = class Foo {}`) —
+    // exercises the class/metadata propagation for the namespace binding so
+    // `new ns(...)` resolves an ImportedClass entry instead of a phantom
+    // `perry_fn_<mod>__default` function wrapper.
+    let cls_pkg = root.join("node_modules").join("fakecls");
+    std::fs::create_dir_all(&cls_pkg).expect("mkdir fakecls");
+    std::fs::write(
+        cls_pkg.join("package.json"),
+        r#"{ "name": "fakecls", "version": "1.0.0", "main": "index.js" }"#,
+    )
+    .expect("write fakecls package.json");
+    std::fs::write(
+        cls_pkg.join("index.js"),
+        "'use strict';\nmodule.exports = class Box { constructor(x) { this.x = x; } doubled() { return this.x * 2; } };\n",
+    )
+    .expect("write fakecls index.js");
+
+    // Consumer imports both as namespaces and CALLS them directly — the exact
+    // ajv `resolve.ts` shape.
+    let entry = root.join("main.ts");
+    std::fs::write(
+        &entry,
+        r#"
+import * as equal from "fakeequal";
+import * as traverse from "faketraverse";
+import * as Box from "fakecls";
+
+const eq: boolean = (equal as any)({ a: 1 }, { a: 1 } as any) === false;
+console.log("equal:", (equal as any)(1, 1), (equal as any)(1, 2));
+
+let seen = 0;
+const doubled: number = (traverse as any)({ n: 21 }, (_s: any) => { seen++; });
+console.log("traverse:", doubled, "seen:", seen);
+console.log("eq_ref:", eq);
+
+// `new` through a namespace binding whose CJS default is a class.
+const b: any = new (Box as any)(21);
+console.log("box:", b.doubled());
+"#,
+    )
+    .expect("write entry");
+
+    let output = root.join("main_bin");
+    let compile = Command::new(perry_bin())
+        .current_dir(root)
+        .arg("compile")
+        .arg(&entry)
+        .arg("-o")
+        .arg(&output)
+        .output()
+        .expect("run perry compile");
+    assert!(
+        compile.status.success(),
+        "perry compile failed (namespace-import-of-CJS-default link wall regressed?)\nstdout:\n{}\nstderr:\n{}",
+        String::from_utf8_lossy(&compile.stdout),
+        String::from_utf8_lossy(&compile.stderr)
+    );
+
+    let run = Command::new(&output).output().expect("run compiled binary");
+    let stdout = String::from_utf8_lossy(&run.stdout);
+    assert!(
+        run.status.success(),
+        "compiled binary failed\nstatus: {:?}\nstdout:\n{}\nstderr:\n{}",
+        run.status,
+        stdout,
+        String::from_utf8_lossy(&run.stderr)
+    );
+    assert_eq!(
+        stdout, "equal: true false\ntraverse: 42 seen: 1\neq_ref: true\nbox: 42\n",
+        "namespace import of a CJS default function/class must resolve the default export"
+    );
+}