fix(#758): --cwd, --date, --session missing-value errors now use missing_flag_value prefix + hint

Author: code-yeongyu

ROADMAP.md

@@ -7681,3 +7681,5 @@ Original filing (2026-04-18): the session emitted `SessionStart hook (completed)
 756. **`--reasoning-effort bogus`, `--model` (no value), and sibling missing/invalid flag-value errors all returned `error_kind:"unknown"` + `hint:null`** — gaebal-gajae pinpoint on `0e8a449e`. All `missing value for --X` and `invalid value for --reasoning-effort` error strings were single-line with no classifier arm. Fix: (a) prefix all with `missing_flag_value:` / `invalid_flag_value:` + `\n` usage hint; (b) add `message.starts_with("missing_flag_value:")` → `"missing_flag_value"` and `message.starts_with("invalid_flag_value:")` → `"invalid_flag_value"` classifier arms. Covers `--model`, `--output-format`, `--permission-mode`, `--base-commit`, `--reasoning-effort`. Regression guard: `flag_value_errors_have_error_kind_and_hint_756` — invalid `--reasoning-effort HIGH` → `invalid_flag_value` + hint with valid values; missing `--model` → `missing_flag_value` + non-null hint. Source: gaebal-gajae dogfood on `0e8a449e`, 2026-05-26.
 
 757. **`--permission-mode bogus` and `--allowedTools` (no value) returned `error_kind:"unknown"` + `hint:null`** — dogfooded 2026-05-26 on `4df14618`. `parse_permission_mode_arg()` error format had no prefix and no `\n`; `--allowedTools` missing-value string was plain. Fix: prefix `parse_permission_mode_arg` error with `invalid_flag_value:` + `\n` valid-values hint (both call sites); prefix `--allowedTools` missing-value with `missing_flag_value:` + `\n` usage hint. Both now classified by existing `missing_flag_value`/`invalid_flag_value` arms added in #756. Source: Jobdori dogfood on `4df14618`, 2026-05-26.
+
+758. **Three remaining `missing value for --X` strings in `parse_init_args` were still untyped** — dogfooded 2026-05-26 on `02d77ae1`. `--cwd`, `--date`, `--session` missing-value errors in the init-args parser used the old plain-string form with no `missing_flag_value:` prefix and no `\n` hint, unlike the main `parse_args` flags fixed in #756/#757. Fix: applied `missing_flag_value:` prefix + `\n` usage hint to all three. `grep '"missing value for --'` now returns zero results outside of test assertions. Source: Jobdori dogfood sweep on `02d77ae1`, 2026-05-26.

rust/crates/rusty-claude-cli/src/main.rs

@@ -1949,16 +1949,17 @@ fn parse_system_prompt_args(
     while index < args.len() {
         match args[index].as_str() {
             "--cwd" => {
-                let value = args
-                    .get(index + 1)
-                    .ok_or_else(|| "missing value for --cwd".to_string())?;
+                let value = args.get(index + 1).ok_or_else(|| {
+                    "missing_flag_value: missing value for --cwd.\nUsage: --cwd <path>".to_string()
+                })?;
                 cwd = PathBuf::from(value);
                 index += 2;
             }
             "--date" => {
-                let value = args
-                    .get(index + 1)
-                    .ok_or_else(|| "missing value for --date".to_string())?;
+                let value = args.get(index + 1).ok_or_else(|| {
+                    "missing_flag_value: missing value for --date.\nUsage: --date <YYYY-MM-DD>"
+                        .to_string()
+                })?;
                 date.clone_from(value);
                 index += 2;
             }
@@ -1991,7 +1992,7 @@ fn parse_export_args(args: &[String], output_format: CliOutputFormat) -> Result<
             "--session" => {
                 let value = args
                     .get(index + 1)
-                    .ok_or_else(|| "missing value for --session".to_string())?;
+                    .ok_or_else(|| "missing_flag_value: missing value for --session.\nUsage: --session <session-id>".to_string())?;
                 session_reference.clone_from(value);
                 index += 2;
             }