refactor: clear clippy code lints across the workspace

Machine-applicable clippy fixes plus three by-hand cleanups; all
semantics-preserving (full workspace test suite green).

Auto-applied (cargo clippy --fix):
- dropped `.clone()` on the Copy type ParamMode (ret_mode/param_mode)
- map_or(false, p) -> is_some_and(p)
- removed redundant closures and an explicit .into_iter()
- useless format!, a needless deref, an as_bytes-after-slice

By hand:
- ailang-codegen: named the loop-frame tuple types (LoopFrame /
  LoopBinderSlot) instead of the bare nested
  Vec<(String, Vec<(String, String, String, Type)>)>, clearing the
  type-complexity lint and documenting what each slot holds.
- ailang-check: collapsed the two identical pass-through arms of the
  Type-Con qualifier (already-dotted / primitive) into one `||` guard.
- ailang-core: converted a stale `///` block (it described a test that
  was relocated, documenting nothing) back to a plain `//` comment.

Remaining clippy output is 16 markdown list-indentation nits in prose
doc comments — doc formatting, not code, left for a docs pass.

crates/ail/tests/ord_int_intercept_ir_pin.rs

@@ -47,7 +47,7 @@ fn emit_ir(fixture: &str) -> String {
 /// call sites (which also mention `@ail_prelude_<sym>(`) don't
 /// match.
 fn extract_fn_body(ir: &str, sym: &str) -> (String, String) {
-    let needle = format!("define ");
+    let needle = "define ".to_string();
     let mut cursor = 0;
     let sym_marker = format!("@ail_prelude_{sym}(");
     loop {

crates/ailang-check/src/lib.rs

@@ -128,7 +128,7 @@ impl Subst {
                 ret: Box::new(self.apply(ret)),
                 effects: effects.clone(),
                 param_modes: param_modes.clone(),
-                ret_mode: ret_mode.clone(),
+                ret_mode: *ret_mode,
             },
             Type::Forall { vars, constraints, body } => Type::Forall {
                 vars: vars.clone(),
@@ -4727,7 +4727,7 @@ fn strip_own_module_qual(t: &Type, module: &str) -> Type {
             params: params.iter().map(|p| strip_own_module_qual(p, module)).collect(),
             param_modes: param_modes.clone(),
             ret: Box::new(strip_own_module_qual(ret, module)),
-            ret_mode: ret_mode.clone(),
+            ret_mode: *ret_mode,
             effects: effects.clone(),
         },
         Type::Var { .. } => t.clone(),
@@ -4756,13 +4756,12 @@ fn strip_own_module_qual(t: &Type, module: &str) -> Type {
 fn rewrite_type_cons(t: &Type, rewrite_bare: &dyn Fn(&str) -> Option<String>) -> Type {
     match t {
         Type::Con { name, args } => {
-            // The first two guards both pass the name through unchanged
-            // but express semantically distinct reasons (already
-            // qualified; primitive needs no qualification). Only a bare,
-            // non-primitive name is offered to `rewrite_bare`.
-            let qualified_name = if name.contains('.') {
-                name.clone()
-            } else if ailang_core::primitives::is_primitive_name(name) {
+            // Pass a name through unchanged if it is already qualified
+            // (contains a dot) or primitive — neither needs qualifying.
+            // Only a bare, non-primitive name is offered to `rewrite_bare`.
+            let qualified_name = if name.contains('.')
+                || ailang_core::primitives::is_primitive_name(name)
+            {
                 name.clone()
             } else {
                 rewrite_bare(name).unwrap_or_else(|| name.clone())
@@ -4784,7 +4783,7 @@ fn rewrite_type_cons(t: &Type, rewrite_bare: &dyn Fn(&str) -> Option<String>) ->
                 .collect(),
             param_modes: param_modes.clone(),
             ret: Box::new(rewrite_type_cons(ret, rewrite_bare)),
-            ret_mode: ret_mode.clone(),
+            ret_mode: *ret_mode,
             effects: effects.clone(),
         },
         Type::Forall { vars, constraints, body } => Type::Forall {

crates/ailang-check/src/linearity.rs

@@ -405,7 +405,7 @@ fn check_fn(
                 ParamMode::Own => 0,
             },
             is_value: param_tys.get(i).map(type_is_value).unwrap_or(false),
-            fn_param_modes: param_tys.get(i).and_then(|t| fn_modes_of(t)),
+            fn_param_modes: param_tys.get(i).and_then(fn_modes_of),
         };
         checker.binders.insert(name.clone(), initial);
     }
@@ -582,7 +582,7 @@ impl<'a> Checker<'a> {
                         .let_binder_types
                         .get(&(self.def_name.to_string(), name.clone()));
                     let is_value = teed.map(type_is_value).unwrap_or(false);
-                    let fn_param_modes = teed.and_then(|t| fn_modes_of(t));
+                    let fn_param_modes = teed.and_then(fn_modes_of);
                     self.with_binder(
                         name,
                         BinderState { is_value, fn_param_modes, ..BinderState::default() },
@@ -684,7 +684,7 @@ impl<'a> Checker<'a> {
                     saved_for_params.insert(p.clone(), self.binders.remove(p));
                     let st = BinderState {
                         is_value: param_tys.get(i).map(type_is_value).unwrap_or(false),
-                        fn_param_modes: param_tys.get(i).and_then(|t| fn_modes_of(t)),
+                        fn_param_modes: param_tys.get(i).and_then(fn_modes_of),
                         ..BinderState::default()
                     };
                     self.binders.insert(p.clone(), st);

crates/ailang-check/src/lower_to_mir.rs

@@ -90,7 +90,7 @@ fn wildcard_residual_metavars(t: &Type) -> Type {
             params: params.iter().map(wildcard_residual_metavars).collect(),
             param_modes: param_modes.clone(),
             ret: Box::new(wildcard_residual_metavars(ret)),
-            ret_mode: ret_mode.clone(),
+            ret_mode: *ret_mode,
             effects: effects.clone(),
         },
         Type::Forall { vars, constraints, body } => Type::Forall {
@@ -486,7 +486,7 @@ fn lower_term(ctx: &mut Ctx, t: &Term) -> Result<MTerm> {
                 .enumerate()
                 .map(|(i, a)| {
                     let mut m = lower_term(ctx, a)?;
-                    if binder_tys.get(i).map_or(false, is_str_ty) {
+                    if binder_tys.get(i).is_some_and(is_str_ty) {
                         if let MTerm::Str { rep, .. } = &mut m {
                             *rep = StrRep::Heap;
                         }

crates/ailang-check/src/mono.rs

@@ -1122,7 +1122,7 @@ fn localize_own_types(t: &Type, defining_module: &str, own_type_names: &BTreeSet
             ret: Box::new(localize_own_types(ret, defining_module, own_type_names)),
             effects: effects.clone(),
             param_modes: param_modes.clone(),
-            ret_mode: ret_mode.clone(),
+            ret_mode: *ret_mode,
         },
         Type::Forall { vars, constraints, body } => Type::Forall {
             vars: vars.clone(),

crates/ailang-codegen/src/drop.rs

@@ -1005,7 +1005,7 @@ impl<'a> Emitter<'a> {
                 (vars, Type::Con { args, .. })
                     if !vars.is_empty() && vars.len() == args.len() =>
                 {
-                    vars.iter().cloned().zip(args.into_iter()).collect()
+                    vars.iter().cloned().zip(args).collect()
                 }
                 _ => BTreeMap::new(),
             };

crates/ailang-codegen/src/lib.rs

@@ -741,6 +741,15 @@ fn main_is_void(t: &Type) -> bool {
     }
 }
 
+/// One loop binder's storage on the recur stack: `(binder name, its
+/// alloca SSA, the LLVM type string, the AILang type)`.
+type LoopBinderSlot = (String, String, String, Type);
+
+/// A loop frame: `(loop header block label, the binder slots active in
+/// that loop)`. Pushed on entry to a `Term::Loop`, popped on exit, and
+/// read by `Term::Recur` to store back into the right allocas.
+type LoopFrame = (String, Vec<LoopBinderSlot>);
+
 struct Emitter<'a> {
     module: &'a Module,
     /// Typed fn bodies for this module (the post-mono `MTerm` per
@@ -917,7 +926,7 @@ struct Emitter<'a> {
     /// it. Saved/reset/restored at the lambda-lowering boundary
     /// alongside `binder_allocas` (a `recur` cannot cross a lambda
     /// boundary).
-    loop_frames: Vec<(String, Vec<(String, String, String, Type)>)>,
+    loop_frames: Vec<LoopFrame>,
     /// Side buffer for `alloca` instructions emitted during body
     /// lowering but hoisted to the fn's entry block. Flushed once
     /// into `self.body` at `entry_block_end_marker` after

crates/ailang-core/src/desugar.rs

@@ -826,7 +826,7 @@ impl Desugarer {
                 free_vars_in_term(&desugared_body, &local_bound, &mut frees);
                 let captures: Vec<String> = frees
                     .iter()
-                    .filter(|f| scope.contains_key(*f))
+                    .filter(|f| scope.contains_key(f))
                     .cloned()
                     .collect();
 

crates/ailang-core/src/workspace.rs

@@ -2387,12 +2387,11 @@ mod tests {
             .expect("qualified Constraint.class in ClassDef-method Forall is the canonical form post-canonical-class-form");
     }
 
-    /// on-disk fixture for `BareCrossModuleTypeRef`. Bare
-    /// `Ordering` Term::Ctor with no imports; the validator catches it
-    /// after prelude injection (so the candidate list contains
-    /// `prelude.Ordering`).
-    // `ct1_fixture_bare_xmod_rejected` relocated to
-    // `crates/ailang-core/tests/workspace_pin.rs` in iter pd.2.
+    // on-disk fixture for `BareCrossModuleTypeRef`. Bare `Ordering`
+    // Term::Ctor with no imports; the validator catches it after
+    // prelude injection (so the candidate list contains
+    // `prelude.Ordering`). `ct1_fixture_bare_xmod_rejected` relocated
+    // to `crates/ailang-core/tests/workspace_pin.rs` in iter pd.2.
 
     /// on-disk fixture for `BadCrossModuleTypeRef`. Qualified
     /// `Mystery.Type` with `Mystery` not a known module.

crates/ailang-core/tests/design_index_pin.rs

@@ -216,7 +216,7 @@ fn contracts_carry_no_decision_record_prose() {
             let mut from = 0;
             while let Some(i) = line[from..].find(kw) {
                 let p = from + i + kw.len();
-                if line[p..].chars().next().map_or(false, |c| c.is_ascii_digit()) {
+                if line[p..].chars().next().is_some_and(|c| c.is_ascii_digit()) {
                     return true;
                 }
                 from = p;
@@ -230,7 +230,7 @@ fn contracts_carry_no_decision_record_prose() {
         if line.contains("21.g") { return Some("21.g"); }
         if let Some(s) = line.find(" sketch") {
             let pre = line[..s].as_bytes();
-            if pre.last().map_or(false, u8::is_ascii_alphanumeric)
+            if pre.last().is_some_and(u8::is_ascii_alphanumeric)
                 && pre.iter().rev()
                       .take_while(|c| c.is_ascii_alphanumeric())
                       .any(u8::is_ascii_digit)