feat(tui): /init writes AGENTS.md in the interface language

Refs #6964. @Asteria1028 asked for `codewhale init` to generate AGENTS.md
in the language Codewhale is using. The /init prompt said "Write in
English." unconditionally. That contradicted the zh-Hans/ja/pt-BR/vi
system-prompt language bookends, and when /translate is on, it also
contradicted the translation requirement. So a Chinese-UI session got an
English file.

What
- CommandPresentationContext (command-contract facets.rs) gains
  language_name(), with a default of "English". Test stubs and other hosts
  need no change.
- The TUI's PresentationAdapter returns ui_locale.translation_target_name().
  This is the same canonical model-facing name the translation seam already
  uses, e.g. "Simplified Chinese (简体中文)".
- /init declares WORKSPACE | PRESENTATION and destructures both, each with
  a safe missing-facet error. It passes the name to build_init_prompt,
  whose style rule now reads "Write the whole file in {language},
  headings included; keep commands, file paths and code identifiers as
  they are." The doc comments that said /init consumes only WORKSPACE are
  corrected.
- CHANGELOG [Unreleased] bullet, mirrored to crates/tui by
  sync-changelog.sh.
- Not changed: the non-interactive `codewhale init` writes a static English
  template (project_context::create_default_agents_md). Localizing it would
  mean translating the template into 15 packs. The CHANGELOG says so.

Verification (source: 16e2e422e9 plus this diff)
- Real TUI in an isolated tmux socket (env -i, scratch HOME, local stub
  provider), typing /init, then reading the request body the stub logged:
  - LC_ALL=zh_CN.UTF-8: "Write the whole file in Simplified Chinese
    (简体中文), headings included; ...", and the UI chrome rendered in
    Chinese ("输入消息…", "思考：max").
  - en_US.UTF-8: "Write the whole file in English, ...".
  - ja_JP.UTF-8: "Write the whole file in Japanese (日本語), ...".
- scripts/dev-cargo.sh clippy --workspace --all-targets --all-features
  --locked -- -D warnings -A clippy::uninlined_format_args
  -A clippy::too_many_arguments -A clippy::unnecessary_map_or: clean.
- scripts/dev-test.sh tui commands::groups::project::init commands::contract
  commands::groups::config: 159 tests run: 159 passed.
  codewhale-portable-config + codewhale-command-contract: 114 passed.
- cargo fmt --check: clean. sync-changelog --check: up to date.
  check-versions --require-dated-release: exit 0.
- npm test: root 101/101, runtime-sdk 19/19, extension-host 420 (413 pass,
  7 skipped), web node 7/7, vitest 772/772. npm run check:web: exit 0.

Not verified: that a real model writes a good Chinese AGENTS.md. The stub
only proves the instruction. Windows was not run.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01NBKbhx19BRbZtvWK8rVKjz

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- `/init` now asks the model to write `AGENTS.md` in the interface language
+  (for example Simplified Chinese when the TUI runs in zh-Hans), headings
+  included, keeping commands, file paths and code identifiers as they are.
+  Before, the prompt always said "Write in English". The non-interactive
+  `codewhale init` template is unchanged and still English
+  ([#6964](https://github.com/codewhale-hq/Codewhale/issues/6964)).
 - A shell command, shell input or verifier that contains an invisible or
   bidirectional Unicode character is now refused before any approval card or
   reviewer call in Ask, Auto-Review and Never. This covers zero-width spaces

crates/command-contract/src/facets.rs

@@ -128,6 +128,10 @@ pub trait CommandWorkspaceContext {
 pub trait CommandPresentationContext {
     /// Resolve a stable message key with its named replacements.
     fn translate(&self, key: &str, replacements: &[(&str, &str)]) -> Result<String, String>;
+
+    fn language_name(&self) -> &'static str {
+        "English"
+    }
 }
 
 /// Portable receipt for a successful atomic media attachment (FEAT-018 D4).

crates/tui/CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- `/init` now asks the model to write `AGENTS.md` in the interface language
+  (for example Simplified Chinese when the TUI runs in zh-Hans), headings
+  included, keeping commands, file paths and code identifiers as they are.
+  Before, the prompt always said "Write in English". The non-interactive
+  `codewhale init` template is unchanged and still English
+  ([#6964](https://github.com/codewhale-hq/Codewhale/issues/6964)).
 - A shell command, shell input or verifier that contains an invisible or
   bidirectional Unicode character is now refused before any approval card or
   reviewer call in Ask, Auto-Review and Never. This covers zero-width spaces

crates/tui/src/commands/contract.rs

@@ -2188,6 +2188,10 @@ impl CommandPresentationContext for PresentationAdapter<'_> {
         apply_named_replacements(&template, replacements)
             .ok_or_else(|| "invalid translation replacement contract".to_string())
     }
+
+    fn language_name(&self) -> &'static str {
+        self.host.app.borrow().ui_locale.translation_target_name()
+    }
 }
 
 /// Resolve session-control and structural-copy runtime keys to the current

crates/tui/src/commands/groups/project/init.rs

@@ -21,10 +21,11 @@ use crate::commands::CommandResult;
 /// delegating content generation to the LLM agent.
 ///
 /// FEAT-021 portable dispatch: consumes only the workspace path (supplied
-/// through the `WORKSPACE` facet); the workspace scan and prompt composition
-/// stay handler-owned (D2). `crate::utils`/`crate::project_context` are leaf,
+/// through the `WORKSPACE` facet) and the UI language name (through the
+/// `PRESENTATION` facet); the workspace scan and prompt composition stay
+/// handler-owned (D2). `crate::utils`/`crate::project_context` are leaf,
 /// path-parameterized helpers (no App/service state), consistent with D8.
-fn init(workspace: &Path) -> CommandResult {
+fn init(workspace: &Path, language: &str) -> CommandResult {
     // Ensure .deepseek/ is gitignored if we're inside a git repo.
     ensure_deepseek_gitignored(workspace);
 
@@ -43,7 +44,12 @@ fn init(workspace: &Path) -> CommandResult {
     };
 
     // Construct the prompt for the LLM agent.
-    let prompt = build_init_prompt(&context, existing_content.as_deref(), already_exists);
+    let prompt = build_init_prompt(
+        &context,
+        existing_content.as_deref(),
+        already_exists,
+        language,
+    );
 
     // Display message to user AND send the prompt to the agent.
     let verb = if already_exists {
@@ -717,6 +723,7 @@ fn build_init_prompt(
     context: &str,
     existing_content: Option<&str>,
     already_exists: bool,
+    language: &str,
 ) -> String {
     let mut prompt = String::new();
 
@@ -746,7 +753,7 @@ fn build_init_prompt(
 
     prompt.push_str("## Instructions\n\n");
 
-    prompt.push_str(
+    prompt.push_str(&format!(
         "1. **Read key source files** to understand the architecture:\n\
            - Start with the main entry point(s) (e.g., main.rs, index.ts, app.py)\n\
            - Read the top-level module structure to understand component boundaries\n\
@@ -781,12 +788,13 @@ fn build_init_prompt(
            - Be concise and actionable. This is a reference document, not a tutorial.\n\
            - Use markdown headings, code blocks, and bullet lists.\n\
            - Keep the total under ~150 lines unless the project genuinely needs more.\n\
-           - Write in English.\n\
+           - Write the whole file in {language}, headings included; keep commands, \
+             file paths and code identifiers as they are.\n\
            - Do NOT include placeholder HTML comments like \"<!-- add stuff here -->\".\n\
            - If you cannot determine something with confidence, omit that section rather than guessing.\n\n\
          4. **Write the file** using the file write tool. \
            The file should be named `AGENTS.md` at the workspace root.\n\n",
-    );
+    ));
 
     if already_exists {
         prompt.push_str(
@@ -822,7 +830,8 @@ impl codewhale_command_contract::metadata::RegisterCommand<crate::commands::Comm
     fn handler()
     -> codewhale_command_contract::handler::CommandHandler<crate::commands::CommandResult> {
         codewhale_command_contract::handler::CommandHandler::Contextual {
-            capabilities: codewhale_command_contract::handler::CommandCapabilities::WORKSPACE,
+            capabilities: codewhale_command_contract::handler::CommandCapabilities::WORKSPACE
+                .union(codewhale_command_contract::handler::CommandCapabilities::PRESENTATION),
             handler: init_contextual,
         }
     }
@@ -830,10 +839,11 @@ impl codewhale_command_contract::metadata::RegisterCommand<crate::commands::Comm
 
 /// Contextual `/init` dispatch (FEAT-021 Phase 4).
 ///
-/// Destructures the declared `WORKSPACE` facet with a safe missing-facet
-/// error. The workspace path is consumed via the `WORKSPACE` facet (D2);
+/// Destructures the declared `WORKSPACE` and `PRESENTATION` facets with safe
+/// missing-facet errors. The workspace path is consumed via the `WORKSPACE`
+/// facet (D2) and the language the file is written in via `PRESENTATION`;
 /// `/init` consumes no project-facet method, so it destructures exactly
-/// `WORKSPACE` (D4, least-capability — the initial PROJECT|WORKSPACE
+/// those two (D4, least-capability — the initial PROJECT|WORKSPACE
 /// declaration was amended after the critical audit; main's model expresses
 /// the declaration as exact facet destructuring rather than a bitmask).
 fn init_contextual(contexts: CommandContexts<'_>, _arg: Option<&str>) -> CommandResult {
@@ -841,7 +851,12 @@ fn init_contextual(contexts: CommandContexts<'_>, _arg: Option<&str>) -> Command
     let Some(workspace) = parts.workspace.as_deref() else {
         return crate::commands::CommandResult::error("Command capability unavailable: workspace");
     };
-    init(&workspace.workspace())
+    let Some(presentation) = parts.presentation.as_deref() else {
+        return crate::commands::CommandResult::error(
+            "Command capability unavailable: presentation",
+        );
+    };
+    init(&workspace.workspace(), presentation.language_name())
 }
 
 // ---------------------------------------------------------------------------
@@ -858,7 +873,7 @@ mod tests {
     #[test]
     fn init_returns_send_message_action() {
         let tmpdir = TempDir::new().unwrap();
-        let result = init(tmpdir.path());
+        let result = init(tmpdir.path(), "English");
         assert!(result.message.is_some());
         let msg = result.message.unwrap();
         assert!(msg.contains("Creating AGENTS.md"));
@@ -872,7 +887,7 @@ mod tests {
     fn init_says_updating_when_agents_md_exists() {
         let tmpdir = TempDir::new().unwrap();
         std::fs::write(tmpdir.path().join("AGENTS.md"), "existing content").unwrap();
-        let result = init(tmpdir.path());
+        let result = init(tmpdir.path(), "English");
         assert!(result.message.unwrap().contains("Updating AGENTS.md"));
         assert!(matches!(result.action, Some(AppAction::SendMessage(_))));
     }
@@ -881,7 +896,7 @@ mod tests {
     fn init_includes_gitignore_handling() {
         let tmpdir = TempDir::new().unwrap();
         std::fs::create_dir_all(tmpdir.path().join(".git")).unwrap();
-        let result = init(tmpdir.path());
+        let result = init(tmpdir.path(), "English");
         assert!(!result.is_error);
         // Should have added .deepseek/ to .gitignore.
         let gi = std::fs::read_to_string(tmpdir.path().join(".gitignore")).unwrap();
@@ -896,7 +911,7 @@ mod tests {
             "[package]\nname = \"test-crate\"\nversion = \"0.1.0\"\n",
         )
         .unwrap();
-        let result = init(tmpdir.path());
+        let result = init(tmpdir.path(), "English");
         let Some(AppAction::SendMessage(prompt)) = result.action else {
             panic!("expected SendMessage action");
         };
@@ -922,7 +937,7 @@ mod tests {
             "# My Project\n\nCustom instructions here.",
         )
         .unwrap();
-        let result = init(tmpdir.path());
+        let result = init(tmpdir.path(), "English");
         let Some(AppAction::SendMessage(prompt)) = result.action else {
             panic!("expected SendMessage action");
         };
@@ -1305,7 +1320,7 @@ mod tests {
     #[test]
     fn build_init_prompt_contains_all_sections() {
         let ctx = "## Project Summary\n\nA Rust project\n";
-        let prompt = build_init_prompt(ctx, None, false);
+        let prompt = build_init_prompt(ctx, None, false, "English");
         assert!(prompt.contains("Project Context"));
         assert!(prompt.contains("A Rust project"));
         assert!(prompt.contains("Read key source files"));
@@ -1318,7 +1333,7 @@ mod tests {
     fn build_init_prompt_with_existing_content() {
         let ctx = "## Project Summary\n\nA Rust project\n";
         let existing = "# Old AGENTS.md content";
-        let prompt = build_init_prompt(ctx, Some(existing), true);
+        let prompt = build_init_prompt(ctx, Some(existing), true, "English");
         assert!(prompt.contains("Old AGENTS.md content"));
         assert!(prompt.contains("Update it in place"));
     }
@@ -1326,7 +1341,7 @@ mod tests {
     #[test]
     fn build_init_prompt_new_file_no_update_instruction() {
         let ctx = "## Project Summary\n\nA Rust project\n";
-        let prompt = build_init_prompt(ctx, None, false);
+        let prompt = build_init_prompt(ctx, None, false, "English");
         assert!(!prompt.contains("The file already exists"));
     }