fix(cli): tighten plan explain error handling

- raise typer.Exit from None to satisfy B904\n- update Behave and Robot tests to expect decision-only errors\n- document the fix in the changelog and add HAL9000 contributor entry\n\nISSUES CLOSED: #6325

CHANGELOG.md

@@ -46,6 +46,13 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   PR–issue label synchronization. The `issue-state-updater` syncs PR state labels whenever
   issue states change.
 
+### Fixed
+
+- **CLI – plan explain** (#6325): `agents plan explain` no longer attempts a
+  plan-ID fallback. It now exits with a decision-specific error message when a
+  plan ULID is provided, and the Behave/Robot regression suites have been
+  updated to assert the corrected behaviour.
+
 ### Changed
 
 - **Automation Tracking Format**: All automation tracking issues now use a standardized

CONTRIBUTORS.md

@@ -3,6 +3,7 @@
 * Aditya Chhabra <aditya.chhabra@cleverthis.com>
 * Brent E. Edwards <brent.edwards@cleverthis.com>
 * Hamza Khyari <hamza.khyari@cleverthis.com>
+* HAL 9000 <hal9000@cleverthis.com>
 * Jeffrey Phillips Freeman <jeffrey.freeman@syncleus.com>
 * Luis Mendes <luis.p.mendes@gmail.com>
 * Rui Hu <rui.hu@cleverthis.com>

features/steps/plan_explain_cli_coverage_steps.py

@@ -16,6 +16,7 @@ from behave.runner import Context
 from typer.testing import CliRunner
 from ulid import ULID
 
+from cleveragents.application.services.decision_service import DecisionNotFoundError
 from cleveragents.application.services.plan_lifecycle_service import (
     InvalidPhaseTransitionError,
 )
@@ -169,8 +170,7 @@ def step_pec_mock_decision_svc(context: Context) -> None:
 def step_pec_mock_decision_none(context: Context) -> None:
     context.pec_decision_id = str(ULID())
     svc = MagicMock()
-    svc.get_decision.return_value = None
-    svc.list_decisions.return_value = []
+    svc.get_decision.side_effect = DecisionNotFoundError(context.pec_decision_id)
     context.pec_container = _mock_container_with_decision_svc(svc)
 
 

robot/helper_tdd_plan_explain_plan_id.py

@@ -185,7 +185,7 @@ def explain_plan_id_shows_question() -> None:
             )
 
         combined: str = (result.stdout + result.stderr).lower()
-        if "what should we build?" in combined or "decision" in combined:
+        if "what should we build?" in combined or "a rest api" in combined:
             _fail(
                 "plan explain output unexpectedly included decision content. "
                 f"stdout: {result.stdout}\n"

src/cleveragents/cli/commands/plan.py

@@ -4217,7 +4217,7 @@ def explain_decision_cmd(
         decision = svc.get_decision(identifier)
     except DecisionNotFoundError:
         console.print(f"[red]Error:[/red] '{identifier}' not found as a decision.")
-        raise typer.Exit(1)
+        raise typer.Exit(1) from None
 
     data = _build_explain_dict(
         decision,