Fix docs preprocessor preferring parameterized keybindings over exact matches (#54593)

This PR fixes a bug with the docs pre-processor where it could match on
parameterized versions of key binds before exact matches.

I noticed this bug in the latest [parallel agent
docs:](https://zed.dev/docs/ai/parallel-agents#switching-threads)

<img width="717" height="110" alt="SCR-20260423-bhtn"
src="https://github.com/user-attachments/assets/ea20b592-55c3-4e92-9c2e-ff821efacdd8"
/>

Here, the preprocessor is matching on the parameterized version first:

```json
"ctrl-tab": "agents_sidebar::ToggleThreadSwitcher",
"ctrl-shift-tab": ["agents_sidebar::ToggleThreadSwitcher", { "select_last": true }],
```

This bug surfaced in some other places in the docs as well:

- https://zed.dev/docs/ai/agent-panel#multiple-threads
- https://zed.dev/docs/finding-navigating#project-search
- https://zed.dev/docs/finding-navigating#quick-reference
- https://zed.dev/docs/migrate/webstorm#no-indexing
- https://zed.dev/docs/migrate/webstorm#differences-in-user-interfaces

Self-Review Checklist:

- [X] I've reviewed my own diff for quality, security, and reliability
- [N/A] Unsafe blocks (if any) have justifying comments
- [N/A] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [X] Tests cover the new/changed behavior
- [X] Performance impact has been considered and is acceptable

Release Notes:

- N/A

crates/docs_preprocessor/src/main.rs

@@ -336,17 +336,28 @@ fn is_missing_action(name: &str) -> bool {
     actions_available() && find_action_by_name(name).is_none()
 }
 
-// Find the binding in reverse order, as the last binding takes precedence.
+// Find the last binding (in keymap order) for the given action.
+// Exact action matches are preferred over parameterized variants.
 fn find_binding_in_keymap(keymap: &KeymapFile, action: &str) -> Option<String> {
-    keymap.sections().rev().find_map(|section| {
-        section.bindings().rev().find_map(|(keystroke, a)| {
-            if name_for_action(a.to_string()) == action {
-                Some(keystroke.to_string())
-            } else {
-                None
-            }
+    let find = |predicate: &dyn Fn(&str) -> bool| {
+        keymap.sections().rev().find_map(|section| {
+            section.bindings().rev().find_map(|(keystroke, a)| {
+                if predicate(&a.to_string()) {
+                    Some(keystroke.to_string())
+                } else {
+                    None
+                }
+            })
         })
-    })
+    };
+
+    // Look for exact match
+    if let Some(binding) = find(&|a| a == action) {
+        return Some(binding);
+    }
+
+    // Look for parameterized match
+    find(&|a| name_for_action(a.to_string()) == action)
 }
 
 fn find_binding(os: Os, action: &str) -> Option<String> {
@@ -872,3 +883,68 @@ fn keymap_schema_for_actions(
         &deprecation_messages,
     )
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    #[test]
+    fn test_find_binding_prefers_exact_match_over_parameterized() {
+        let keymap: KeymapFile = serde_json::from_value(json!([
+            {
+                "bindings": {
+                    "ctrl-tab": "agents_sidebar::ToggleThreadSwitcher",
+                    "ctrl-shift-tab": ["agents_sidebar::ToggleThreadSwitcher", { "select_last": true }]
+                }
+            }
+        ]))
+        .unwrap();
+
+        let binding = find_binding_in_keymap(&keymap, "agents_sidebar::ToggleThreadSwitcher");
+        assert_eq!(binding.as_deref(), Some("ctrl-tab"));
+    }
+
+    #[test]
+    fn test_find_binding_falls_back_to_parameterized_match() {
+        let keymap: KeymapFile = serde_json::from_value(json!([
+            {
+                "bindings": {
+                    "ctrl-shift-tab": ["agents_sidebar::ToggleThreadSwitcher", { "select_last": true }]
+                }
+            }
+        ]))
+        .unwrap();
+
+        let binding = find_binding_in_keymap(&keymap, "agents_sidebar::ToggleThreadSwitcher");
+        assert_eq!(binding.as_deref(), Some("ctrl-shift-tab"));
+    }
+
+    #[test]
+    fn test_find_binding_prefers_exact_match_regardless_of_order() {
+        let keymap: KeymapFile = serde_json::from_value(json!([
+            {
+                "bindings": {
+                    "ctrl-shift-tab": ["agents_sidebar::ToggleThreadSwitcher", { "select_last": true }],
+                    "ctrl-tab": "agents_sidebar::ToggleThreadSwitcher"
+                }
+            }
+        ]))
+        .unwrap();
+
+        let binding = find_binding_in_keymap(&keymap, "agents_sidebar::ToggleThreadSwitcher");
+        assert_eq!(binding.as_deref(), Some("ctrl-tab"));
+    }
+
+    #[test]
+    fn test_find_binding_later_section_overrides_earlier() {
+        let keymap: KeymapFile = serde_json::from_value(json!([
+            { "bindings": { "ctrl-a": "some::Action" } },
+            { "bindings": { "ctrl-b": "some::Action" } }
+        ]))
+        .unwrap();
+
+        let binding = find_binding_in_keymap(&keymap, "some::Action");
+        assert_eq!(binding.as_deref(), Some("ctrl-b"));
+    }
+}