[alex09x]

Problem

code_outline with exported_only treats a Rust impl block as transparent (#1418): it passes on its owners' visibility, which at the top level is none. So for

struct Hidden;
impl Hidden {
    pub fn new() -> Self { Hidden }
}

the outline left Hidden out but listed impl Hidden and new, which nothing outside the crate can reach (#1587).

Change

tools/outline/render.rs:

• A pre-pass records whether each type the file declares at the top level (struct, enum, trait, class) is exported.
• A Rust impl header is read for its trait and self type by impl_types, which takes each by its last path segment, skips generics, and stops at where/{. Examples:
  • impl<T: Clone> Shown<T> → Shown;
  • impl fmt::Display for W<'a> → Display and W.
• If either the trait or the self type is declared in the file and is not exported, the impl and its members are not exported.
• A type the file does not declare is not judged, so the previous behaviour stands for it.

Reproduce and verify

New test tests/outline_exported_owners.rs::an_impl_of_a_private_type_exports_none_of_its_members. impl Hidden's new is left out, and impl<T: Clone> Shown<T>'s get is listed.

Before (the check disabled, a Linux build node):

new: Outline for src/lib.rs:
  [Symbol] impl Hidden (line 2)

After: passes. The two existing tests in that file still pass.

Measurements

None.

Checks

One gate on a Linux build node (default stable toolchain) covered this PR together with #1582, the other mcp fix merged with it. The two change disjoint files.

• cargo test -p prod-code-mcp --no-fail-fast: exit 101. 134 of 134 binaries ran. The one failed target is --test encapsulate_preservation (context_review::rust_consuming_receiver_keeps_unconditional_rhs), the known environment failure of Two prod-code-mcp tests depend on the build node: /tmp as a workspace root and an unconditional zig probe #1567, unrelated.
• cargo clippy -p prod-code-mcp --all-targets: exit 0. The one warning in a touched file, collapsible_if at tools/symbols/resolve.rs:367, is on a pre-existing line (main's line 361, moved by this change).
• cargo fmt --all -- --check: exit 0.

Closes #1587