Feature: Decision correction recomputes only affected subtree
  As a developer using CleverAgents correction flows
  I want corrections to recompute only the affected subtree
  So that sibling and ancestor decisions are preserved unchanged

  Background:
    Given a subtree isolation correction service
    And a subtree isolation decision tree with root "root" and children
      | parent | children  |
      | root   | A,B       |
      | A      | C,D       |
      | B      | E         |

  # --- Leaf targeting ---

  Scenario: Correction targets leaf node - only leaf affected
    When I subtree isolate target decision "D" with mode "revert"
    And I subtree isolate analyze the impact
    Then the subtree isolate affected decisions should be "D"
    And the subtree isolate excluded decisions should contain "root"
    And the subtree isolate excluded decisions should contain "A"
    And the subtree isolate excluded decisions should contain "B"
    And the subtree isolate excluded decisions should contain "C"
    And the subtree isolate excluded decisions should contain "E"

  # --- Middle node targeting ---

  Scenario: Correction targets middle node - middle and descendants affected
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate analyze the impact
    Then the subtree isolate affected decisions should contain "A"
    And the subtree isolate affected decisions should contain "C"
    And the subtree isolate affected decisions should contain "D"
    And the subtree isolate excluded decisions should contain "root"
    And the subtree isolate excluded decisions should contain "B"
    And the subtree isolate excluded decisions should contain "E"

  # --- Root targeting ---

  Scenario: Correction targets root - all decisions affected with tier 0 warning
    When I subtree isolate target decision "root" with mode "revert"
    And I subtree isolate generate a dry-run report
    Then the subtree isolate affected decisions should contain "root"
    And the subtree isolate affected decisions should contain "A"
    And the subtree isolate affected decisions should contain "B"
    And the subtree isolate affected decisions should contain "C"
    And the subtree isolate affected decisions should contain "D"
    And the subtree isolate affected decisions should contain "E"
    And the subtree isolate excluded decisions should be empty
    And the subtree isolate rollback tier depth should be 0
    And the subtree isolate dry-run warnings should contain "Tier 0"

  # --- Rollback tier computation ---

  Scenario: Rollback tier is 0 for root
    When I subtree isolate compute rollback tier for "root"
    Then the subtree isolate rollback tier should be 0

  Scenario: Rollback tier is 1 for direct child
    When I subtree isolate compute rollback tier for "A"
    Then the subtree isolate rollback tier should be 1

  Scenario: Rollback tier is 1 for second direct child
    When I subtree isolate compute rollback tier for "B"
    Then the subtree isolate rollback tier should be 1

  Scenario: Rollback tier is 2 for grandchild
    When I subtree isolate compute rollback tier for "C"
    Then the subtree isolate rollback tier should be 2

  Scenario: Rollback tier depth 3 for deep tree
    Given a subtree isolation deep tree with depth 4
    When I subtree isolate compute rollback tier for "depth_3"
    Then the subtree isolate rollback tier should be 3

  # --- Dry-run report enhancements ---

  Scenario: Dry-run report includes excluded decisions and rollback tier
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate generate a dry-run report
    Then the subtree isolate dry-run report should include excluded decisions
    And the subtree isolate dry-run report rollback tier depth should be 1
    And the subtree isolate dry-run report excluded decisions should contain "root"
    And the subtree isolate dry-run report excluded decisions should contain "B"
    And the subtree isolate dry-run report excluded decisions should contain "E"

  # --- Subtree isolation validation ---

  Scenario: Subtree isolation is valid for non-root target
    When I subtree isolate validate isolation for target "A"
    Then the subtree isolate isolation should be valid

  Scenario: Subtree isolation is valid for leaf target
    When I subtree isolate validate isolation for target "D"
    Then the subtree isolate isolation should be valid

  # --- Edge cases for coverage ---

  Scenario: Subtree isolation with empty tree returns valid
    Given a subtree isolation empty tree
    When I subtree isolate validate isolation for target "X"
    Then the subtree isolate isolation should be valid

  Scenario: Rollback tier for unknown node is 0
    When I subtree isolate compute rollback tier for "UNKNOWN"
    Then the subtree isolate rollback tier should be 0

  Scenario: Find parent returns None for root node
    When I subtree isolate check parent of "root"
    Then the subtree isolate parent should be none

  # --- Influence DAG traversal ---

  Scenario: Influence edge adds extra decision to affected set
    Given a subtree isolate influence edge from "D" to "E"
    When I subtree isolate target decision "D" with mode "revert"
    And I subtree isolate analyze the impact with influence edges
    Then the subtree isolate affected decisions should contain "D"
    And the subtree isolate affected decisions should contain "E"
    And the subtree isolate excluded decisions should contain "root"
    And the subtree isolate excluded decisions should contain "A"
    And the subtree isolate excluded decisions should contain "B"
    And the subtree isolate excluded decisions should contain "C"

  Scenario: Influence DAG cycle does not cause infinite loop
    Given a subtree isolate influence cycle from "C" to "D" back to "C"
    When I subtree isolate target decision "C" with mode "revert"
    And I subtree isolate analyze the impact with influence edges
    Then the subtree isolate affected decisions should contain "C"
    And the subtree isolate affected decisions should contain "D"

  Scenario: Isolation validation passes when influence DAG reaches sibling
    Given a subtree isolate influence edge from "D" to "E"
    When I subtree isolate validate isolation for target "D" with influence edges
    Then the subtree isolate isolation should be valid

  # --- Append mode ---

  Scenario: Append correction spawns child plan
    When I subtree isolate target decision "A" with mode "append"
    And I subtree isolate execute append correction
    Then the subtree isolate append result should have a spawned child plan
    And the subtree isolate append result status should be "applied"

  # --- Dry-run enforcement ---

  Scenario: Executing a dry-run revert correction raises ValidationError
    When I subtree isolate target decision "A" with mode "revert" and dry_run
    Then subtree isolate executing the correction should raise a dry-run error

  Scenario: Executing a dry-run append correction raises ValidationError
    When I subtree isolate target decision "A" with mode "append" and dry_run
    Then subtree isolate executing the correction should raise a dry-run error

  # --- Negative isolation validation ---

  Scenario: Isolation validation detects structural root contamination
    Given a subtree isolation tree where child structurally reaches root
      | parent | children  |
      | root   | A         |
      | A      | root      |
    When I subtree isolate validate isolation for target "A"
    Then the subtree isolate isolation should be invalid

  # --- Execute revert (non-dry-run) ---

  Scenario: Execute revert correction succeeds for middle node
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate execute revert correction
    Then the subtree isolate revert result status should be "applied"
    And the subtree isolate revert result should contain reverted decisions "A,C,D"
    And the subtree isolate revert result should have archived artifacts

  # --- Status guard enforcement ---

  Scenario: Executing an already-applied correction raises ValidationError
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate execute revert correction
    Then subtree isolate executing the correction again should raise a status error

  Scenario: Executing a cancelled correction raises ValidationError
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate cancel the correction
    Then subtree isolate executing the correction should raise a status error

  # --- Mode mismatch enforcement ---

  Scenario: Calling execute_revert on an append correction raises ValidationError
    When I subtree isolate target decision "A" with mode "append"
    Then subtree isolate calling execute_revert should raise a mode error

  Scenario: Calling execute_append on a revert correction raises ValidationError
    When I subtree isolate target decision "A" with mode "revert"
    Then subtree isolate calling execute_append should raise a mode error

  # --- Single-node tree edge case ---

  Scenario: Single-node tree has no excluded decisions
    Given a subtree isolation single node tree
    When I subtree isolate target decision "root" with mode "revert"
    And I subtree isolate analyze the impact
    Then the subtree isolate affected decisions should be "root"
    And the subtree isolate excluded decisions should be empty
    And the subtree isolate rollback tier depth should be 0

  # --- Terminal state guard ---

  Scenario: Re-analyzing an applied correction raises ValidationError
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate execute revert correction
    Then subtree isolate re-analyzing the impact should raise a terminal state error

  # --- Exact-match affected set for middle node ---

  Scenario: Middle node affected count is exactly 3
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate analyze the impact
    Then the subtree isolate affected decisions count should be 3

  # --- Convergent (diamond) DAG topology ---

  Scenario: Convergent diamond topology does not duplicate affected nodes
    Given a subtree isolate diamond influence where "C" and "D" both target "E"
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate analyze the impact with influence edges
    Then the subtree isolate affected decisions should contain "C"
    And the subtree isolate affected decisions should contain "D"
    And the subtree isolate affected decisions should contain "E"
    And the subtree isolate affected decision "E" should appear exactly once

  # --- Dry-run exception recovery ---

  Scenario: Dry-run report restores status when analyze_impact fails
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate generate a dry-run report that fails internally
    Then the subtree isolate correction status should be "pending"

  # --- Execute revert with influence edges ---

  Scenario: Execute revert with influence edges includes DAG-reachable decisions
    Given a subtree isolate influence edge from "D" to "E"
    When I subtree isolate target decision "A" with mode "revert"
    And I subtree isolate execute revert correction with influence edges
    Then the subtree isolate revert result status should be "applied"
    And the subtree isolate revert result should contain reverted decision "E"

  # --- DAG-only nodes in excluded set ---

  Scenario: Nodes only in influence DAG appear in excluded set
    Given a subtree isolate influence edge from "X_EXT" to "Y_EXT" only in DAG
    When I subtree isolate target decision "D" with mode "revert"
    And I subtree isolate analyze the impact with influence edges
    Then the subtree isolate excluded decisions should contain "X_EXT"
    And the subtree isolate excluded decisions should contain "Y_EXT"