Add a new implementation-pool-supervisor.md agent definition wrapping the
implementation supervisor for pool operations, with an embedded mandatory
8-item PR Compliance Checklist. Workers must complete all 8 items before
creating a PR: CHANGELOG.md update, CONTRIBUTORS.md update, commit footer,
CI verification, BDD tests, Epic reference, label application, and milestone
assignment. Includes concrete markdown examples for each subsection and
compliance verification pseudocode to ensure reproducible adherence.

Parent Epic: #9779

ISSUES CLOSED: #10069

@@ -0,0 +8,4 @@
+  recommends a higher tier, giving progressive escalation across attempts.
+mode: all
+hidden: false
+temperature: 0.0

@@ -0,0 +232,4 @@
+
+### `implementation-supervisor`
+
+#### How to invoke

@@ -0,0 +1,58 @@
+@mock_only

@@ -0,0 +8,4 @@
+  recommends a higher tier, giving progressive escalation across attempts.
+mode: all
+hidden: false
+temperature: 0.0

@@ -13,6 +13,21 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   traceback in the structlog warning entry. Removed `@tdd_expected_fail` tag
   from the TDD test so both scenarios run as normal regression guards. (#988)
 
+### Added

@@ -0,0 +1,58 @@
+@mock_only

@@ -13,6 +13,21 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   traceback in the structlog warning entry. Removed `@tdd_expected_fail` tag
   from the TDD test so both scenarios run as normal regression guards. (#988)
 

@@ -0,0 +1,58 @@
+@mock_only

@@ -13,6 +13,21 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   traceback in the structlog warning entry. Removed `@tdd_expected_fail` tag
   from the TDD test so both scenarios run as normal regression guards. (#988)

@@ -0,0 +1,58 @@
+@mock_only

@@ -0,0 +134,4 @@
+```markdown
+## [Unreleased]
+
+### Fixed

@@ -0,0 +155,4 @@
+
+Example commit message:
+
+```

@@ -107,1 +97,3 @@
-- **Plan Rollback Command** (#8557): Implemented `agents plan rollback <plan-id> [<checkpoint-id>]` for checkpoint-based plan state restoration in Epic #8493. The command restores a plan's sandbox to the state captured at a given checkpoint, discarding all decisions made after that checkpoint. The checkpoint can be specified as an optional positional second argument or via the `--to-checkpoint` named option. Supports `--yes/-y` flag to skip confirmation prompts and `--format/-f` for output format selection (rich/plain/json/yaml). Included with comprehensive BDD test coverage (>= 97%) and spec-aligned output formatting showing rollback summary, changes reverted, impact analysis, and post-rollback state panels.
+- **Plan Rollback Command** (#8557): Implemented `agents plan rollback <plan-id> [<checkpoint-id>]` for checkpoint-based plan state restoration in Epic #8493. The command restores a plan's sandbox to the state captured at a given checkpoint, discarding all decisions made after that checkpoint. The checkpoint can be specified as an optional positional second argument or via the `--tocheckpoint` named option. Supports `--yes/-y` flag to skip confirmation prompts and `--format/-f` for output format selection (rich/plain/json/yaml). Included with comprehensive BDD test coverage (>= 97%) and spec-aligned output formatting showing rollback summary, changes reverted, impact analysis, and post-rollback state panels.
+
+- **Implementation Pool Supervisor** (#10069): Added a new