docs: add CHANGELOG and CONTRIBUTORS entries for #9096 decision_id fix

CHANGELOG.md

@@ -7,6 +7,15 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Fixed
 
+- **Plan Tree JSON Missing `decision_id` Field** (#9096): Fixed a bug where
+  `agents plan tree <PLAN_ID> --format json` did not include the `decision_id`
+  field in each tree node. The JSON output now correctly wraps the tree array in
+  a `{"data": [...]}` envelope and each node contains `decision_id` as a
+  top-level key, enabling programmatic consumers to identify individual decisions
+  from the tree output. The `@tdd_expected_fail` tag has been removed from the
+  `@tdd_issue_4254` scenario in `features/plan_explain.feature` as the test now
+  passes.
+
 - **TDD Non-AssertionError Guard Visibility** (#8294): `apply_tdd_inversion` in
   `features/environment.py` now emits its non-assertion exception guard warning to
   both the structured logger and `stderr` via a new `_warning_with_stderr` helper.

CONTRIBUTORS.md

@@ -19,5 +19,6 @@ Below are some of the specific details of various contributions.
 * HAL 9000 has contributed concurrency safety improvements, including thread-safe context tier management (issue #7547) for parallel plan execution.
 * HAL 9000 has contributed the plan concurrency race-condition fix (#7989): wired `LockService` into the plan lifecycle, guarding `execute_plan()` and `apply_plan()` with plan-level advisory locks and unique per-invocation owner identities to prevent silent concurrent state corruption.
 * HAL 9000 has contributed the plugin entry point security hardening fix (#7476): enforced entry point allowlist validation before importing plugin modules to prevent malicious plugin loading.
+* HAL 9000 has contributed the plan tree JSON `decision_id` fix (#9096): updated `step_tree_json_valid` to correctly handle the `{"data": [...]}` envelope structure and removed `@tdd_expected_fail` from the `@tdd_issue_4254` scenario.
 * This project was made possible thanks to considerable donation of time, money, and resources by CleverThis, Inc.
 * HAL 9000 has contributed automated bug fixes, CLI output formatting improvements, and ongoing maintenance as part of the CleverAgents automation system.