fix(tools): probe the action enum with pointer_mut and guard the Run arm (#5944 follow-up)

Maintainer follow-up on @gaord's fix, applying the two review nits:

- The read-only projection probes with
  schema.pointer_mut("/properties/action/enum"), the same idiom
  tools/subagent already uses for this exact bug, so the two sites read as
  one pattern.
- The Run arm two lines above still auto-vivified "properties" on a schema
  without one; it now uses get_mut and cannot write "properties": null.
- Rebased onto current main (the tests module had grown a neighbour) and
  added the changelog receipt crediting the author.

RUST_MIN_STACK=16777216 cargo test -p codewhale-tui --lib -- tools::registry:
51 passed; 0 failed. cargo fmt --check clean; cargo clippy -p codewhale-tui
--lib --all-targets -D warnings clean; sync-changelog --check clean.

No-Issue: community fix from a live Fleet 400 report; no tracking issue.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SJrzNAmppg4vt3LNJbaeri
Signed-off-by: CodeWhale Bot <bot@codewhale.net>

Author: CodeWhale Bot

CHANGELOG.md

@@ -477,6 +477,14 @@ Reports and reproductions that shaped this release:
 
 ### Fixed
 
+- Read-only Fleet workers no longer send `"action": {"enum": null}` in their
+  projected `bash` schema. The read-only projection probed the action enum
+  with a mutating index, which auto-vivified the key on schemas that have no
+  action property, and strict OpenAI-compatible validators then rejected the
+  whole request (`null is not of type "array"`). The probe is non-mutating
+  now, in both the read-only projection and the `Run` arm next to it, and a
+  regression test walks the whole projected catalog for nulls
+  (#5944, thanks @gaord).
 - Fast typing no longer corrupts the composer. The paste-burst heuristic ran
   on every session until a real bracketed paste arrived, holding, buffering,
   retro-grabbing, and absorbing Enter on timing guesses; it is now

crates/tui/CHANGELOG.md

@@ -477,6 +477,14 @@ Reports and reproductions that shaped this release:
 
 ### Fixed
 
+- Read-only Fleet workers no longer send `"action": {"enum": null}` in their
+  projected `bash` schema. The read-only projection probed the action enum
+  with a mutating index, which auto-vivified the key on schemas that have no
+  action property, and strict OpenAI-compatible validators then rejected the
+  whole request (`null is not of type "array"`). The probe is non-mutating
+  now, in both the read-only projection and the `Run` arm next to it, and a
+  regression test walks the whole projected catalog for nulls
+  (#5944, thanks @gaord).
 - Fast typing no longer corrupts the composer. The paste-burst heuristic ran
   on every session until a real bracketed paste arrived, holding, buffering,
   retro-grabbing, and absorbing Enter on timing guesses; it is now

crates/tui/src/tools/registry.rs

@@ -505,25 +505,24 @@ fn project_readonly_evidence_schema(name: &str, schema: &mut Value) {
     if name == "Run" {
         // The shared classifier remains authoritative for `args`; the schema
         // removes the only field that can name verifier programs.
-        if let Some(properties) = schema["properties"].as_object_mut() {
+        if let Some(properties) = schema.get_mut("properties").and_then(Value::as_object_mut) {
             properties.remove("commands");
         }
         return;
     }
-    // Probe with `get_mut`, never `schema["properties"]["action"]["enum"]`:
+    // Probe with `pointer_mut`, never `schema["properties"]["action"]["enum"]`:
     // serde_json's IndexMut auto-vivifies missing keys by inserting Null, so
     // the old probe left `properties.action = {"enum": null}` inside schemas
     // that have no action property (e.g. lowercase `bash`). Strict
     // OpenAI-compatible validators then reject the whole request with
     // `Invalid schema for function 'bash': null is not of type "array"`
     // (observed on Fleet read-only workers; see registry tests).
-    let Some(properties) = schema.get_mut("properties").and_then(Value::as_object_mut) else {
-        return;
-    };
-    let Some(action) = properties.get_mut("action") else {
-        return;
-    };
-    let Some(actions) = action.get_mut("enum").and_then(Value::as_array_mut) else {
+    // The same probe idiom lives in `tools/subagent` (grep `pointer_mut(
+    // "/properties/action/enum")`); keep the two sites greppable as one.
+    let Some(actions) = schema
+        .pointer_mut("/properties/action/enum")
+        .and_then(Value::as_array_mut)
+    else {
         return;
     };
     match name {

crates/tui/src/tools/registry/tests.rs

@@ -1802,6 +1802,8 @@ fn a_builder_upgrade_replaces_the_tool_instead_of_registering_it_twice() {
             .any(|tool| tool.name() == "apply_patch"),
         "the upgrade still adds apply_patch"
     );
+}
+
 /// Regression probe for the fleet-52663788 class of provider 400
 /// (`Invalid schema for function 'bash': null is not of type "array"`):
 /// a read-only Fleet worker (reviewer) projects its tool schemas before the