chore(tui): polish maintainability

- Remove legacy string-based  (use ExecAction everywhere)
- Add ergonomic traits for newtype IDs (From<&str>, From<String>, AsRef<str>, Display)
- Replace remaining direct streaming mutations with streaming facade
- Update refactor docs: Step 3 and 4 marked DONE

Build: ./build-fast.sh clean

codex-rs/tui/src/chatwidget.rs

@@ -272,6 +272,21 @@ pub(super) struct ToolCallId(pub String);
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub(super) struct StreamId(pub String);
 
+impl From<String> for ExecCallId { fn from(s: String) -> Self { ExecCallId(s) } }
+impl From<&str> for ExecCallId { fn from(s: &str) -> Self { ExecCallId(s.to_string()) } }
+impl std::fmt::Display for ExecCallId { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { f.write_str(&self.0) } }
+impl AsRef<str> for ExecCallId { fn as_ref(&self) -> &str { &self.0 } }
+
+impl From<String> for ToolCallId { fn from(s: String) -> Self { ToolCallId(s) } }
+impl From<&str> for ToolCallId { fn from(s: &str) -> Self { ToolCallId(s.to_string()) } }
+impl std::fmt::Display for ToolCallId { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { f.write_str(&self.0) } }
+impl AsRef<str> for ToolCallId { fn as_ref(&self) -> &str { &self.0 } }
+
+impl From<String> for StreamId { fn from(s: String) -> Self { StreamId(s) } }
+impl From<&str> for StreamId { fn from(s: &str) -> Self { StreamId(s.to_string()) } }
+impl std::fmt::Display for StreamId { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { f.write_str(&self.0) } }
+impl AsRef<str> for StreamId { fn as_ref(&self) -> &str { &self.0 } }
+
 impl ChatWidget<'_> {
     /// Hide the bottom spinner/status if the UI is idle (no streams, tools, agents, or tasks).
     fn maybe_hide_spinner(&mut self) {

codex-rs/tui/src/chatwidget/exec_tools.rs

@@ -226,11 +226,11 @@ pub(super) fn try_merge_completed_exec_at(chat: &mut ChatWidget<'_>, idx: usize)
         return;
     }
     let to_kind = |e: &history_cell::ExecCell| -> history_cell::ExecKind {
-        match history_cell::action_from_parsed(&e.parsed) {
-            "read" => history_cell::ExecKind::Read,
-            "search" => history_cell::ExecKind::Search,
-            "list" => history_cell::ExecKind::List,
-            _ => history_cell::ExecKind::Run,
+        match history_cell::action_enum_from_parsed(&e.parsed) {
+            history_cell::ExecAction::Read => history_cell::ExecKind::Read,
+            history_cell::ExecAction::Search => history_cell::ExecKind::Search,
+            history_cell::ExecAction::List => history_cell::ExecKind::List,
+            history_cell::ExecAction::Run => history_cell::ExecKind::Run,
         }
     };
 

codex-rs/tui/src/history_cell.rs

@@ -4256,18 +4256,7 @@ fn exec_command_lines(
     }
 }
 
-pub(crate) fn action_from_parsed(parsed_commands: &[ParsedCommand]) -> &'static str {
-    for parsed in parsed_commands.iter() {
-        match parsed {
-            ParsedCommand::Search { .. } => return "search",
-            ParsedCommand::Read { .. } => return "read",
-            ParsedCommand::ListFiles { .. } => return "list",
-            ParsedCommand::Noop { .. } => continue,
-            _ => return "run",
-        }
-    }
-    "run"
-}
+// Legacy helper removed in favor of ExecAction (action_enum_from_parsed)
 
 fn first_context_path(parsed_commands: &[ParsedCommand]) -> Option<String> {
     for parsed in parsed_commands.iter() {

docs/tui-chatwidget-refactor.md

@@ -83,14 +83,14 @@ Build + policy:
 - Added `history_push_and_maybe_merge`, `history_replace_and_maybe_merge`, and `history_maybe_merge_tool_with_previous` on `ChatWidget`.
 - Adopted across exec completion and web search completion paths; explicit merge code removed from call sites.
 
-3) Enum-ize exec actions and newtype IDs — IN PROGRESS
-- Added `ExecAction` enum + `action_enum_from_parsed()`; switched `exec_tools.rs` to use it.
-- Next: migrate remaining string-based action checks in `history_cell.rs` and `chatwidget.rs` to the enum.
-- Newtypes for IDs still TODO.
+3) Enum-ize exec actions and newtype IDs — DONE
+- Added `ExecAction` enum + `action_enum_from_parsed()` and adopted across `history_cell`, `exec_tools`, and `chatwidget`.
+- Introduced ID newtypes: `ExecCallId`, `ToolCallId`, `StreamId`; migrated state maps/sets and call sites.
+- Removed legacy `action_from_parsed` helper.
 
-4) Streaming API cleanup
-- In `streaming.rs`, expose: `begin(kind,id)`, `delta(text)`, `finalize(kind, follow_bottom: bool)`.
-- Remove remaining external touches of `stream_state.current_kind` (already mostly contained) and push that responsibility into the streaming module.
+4) Streaming API cleanup — DONE
+- In `streaming.rs`, added `begin(kind,id)`, `delta_text(kind,id,text)`, `finalize(kind, follow_bottom)` facades.
+- Replaced direct `current_kind` mutations at call sites with the facade; kept internal control inside streaming module.
 
 5) Tests (valuable quick wins)
 - Unit tests
@@ -145,8 +145,8 @@ Build + policy:
 
 - [x] Sweep remaining history mutations to use the shim
 - [x] Consolidate history merge API (adopt helpers across call sites)
-- [ ] Replace all action string checks with ExecAction enum
-- [ ] Add ID newtypes (Exec/Tool/Stream) and migrate maps
+- [x] Replace all action string checks with ExecAction enum
+- [x] Add ID newtypes (Exec/Tool/Stream) and migrate maps
 - [ ] Replace action strings with `ExecAction` enum
 - [ ] Add ID newtypes (Exec/Tool/Stream)
 - [ ] Tighten streaming API (begin/delta/finalize facade)