@phase2 @acms @scope_chain_resolver
Feature: Pluggable scope chain resolution extension API
  As a CleverAgents developer
  I want a pluggable scope chain resolver registry with prioritized resolvers
  So that the ACMS context assembly pipeline can resolve scope references via registered extensions

  # ---------------------------------------------------------------------------
  # ScopeResolutionContext
  # ---------------------------------------------------------------------------

  @scope_resolution_context
  Scenario: Create ScopeResolutionContext with required scope only
    When I create a ScopeResolutionContext with scope "issue:123"
    Then the ScopeResolutionContext scope should be "issue:123"
    And the ScopeResolutionContext metadata should be empty
    And the ScopeResolutionContext resolved_fragments should be empty

  @scope_resolution_context
  Scenario: Create ScopeResolutionContext with all fields populated
    When I create a full ScopeResolutionContext with scope "pr:456" and metadata key "repo" value "core" and resolved_fragment "frag1"
    Then the ScopeResolutionContext scope should be "pr:456"
    And the ScopeResolutionContext metadata key "repo" should be "core"
    And the ScopeResolutionContext resolved_fragments should contain "frag1"

  # ---------------------------------------------------------------------------
  # ScopeResolverRegistry — resolution
  # ---------------------------------------------------------------------------

  @scope_resolver_registry
  Scenario: Empty registry resolves to empty list
    Given a fresh ScopeResolverRegistry
    When I resolve scope "issue:999" with the registry
    Then the resolution result should be empty

  @scope_resolver_registry
  Scenario: Register a resolver and resolve a matching scope
    Given a fresh ScopeResolverRegistry
    When I register a resolver named "test" with priority 0 that returns "frag_A" for scope "issue:1"
    And I resolve scope "issue:1" with the registry
    Then the resolution result should contain "frag_A"

  @scope_resolver_registry
  Scenario: Higher priority resolver wins over lower priority resolver
    Given a fresh ScopeResolverRegistry
    When I register a resolver named "low" with priority 1 that returns "low_frag" for scope "item:1"
    And I register a resolver named "high" with priority 10 that returns "high_frag" for scope "item:1"
    And I resolve scope "item:1" with the registry
    Then the resolution result should contain "high_frag"
    And the resolution result should not contain "low_frag"

  @scope_resolver_registry
  Scenario: First matching resolver wins and stops iteration
    Given a fresh ScopeResolverRegistry
    When I register a resolver named "alpha" with priority 5 that returns "alpha_frag" for scope "x:1"
    And I register a resolver named "beta" with priority 3 that returns "beta_frag" for scope "x:1"
    And I resolve scope "x:1" with the registry
    Then the resolution result should contain "alpha_frag"
    And the resolution result should not contain "beta_frag"

  @scope_resolver_registry
  Scenario: Resolve returns empty when no resolver matches the scope
    Given a fresh ScopeResolverRegistry
    When I register a null resolver named "no_match" with priority 0
    And I resolve scope "unknown:1" with the registry
    Then the resolution result should be empty

  # ---------------------------------------------------------------------------
  # ScopeResolverRegistry — register / unregister
  # ---------------------------------------------------------------------------

  @scope_resolver_registry @register
  Scenario: Register a resolver with explicit priority stores it correctly
    Given a fresh ScopeResolverRegistry
    When I register a null resolver named "myresolver" with priority 42
    Then the registry should contain a resolver named "myresolver"
    And the resolver named "myresolver" should have priority 42

  @scope_resolver_registry @unregister
  Scenario: Unregister removes an existing resolver
    Given a fresh ScopeResolverRegistry
    When I register a null resolver named "to_remove" with priority 0
    And I unregister the resolver named "to_remove"
    Then the registry should not contain a resolver named "to_remove"

  @scope_resolver_registry @unregister
  Scenario: Unregister non-existent resolver is a safe no-op
    Given a fresh ScopeResolverRegistry
    When I unregister the resolver named "does_not_exist"
    Then the registry should not contain a resolver named "does_not_exist"

  # ---------------------------------------------------------------------------
  # ScopeResolverRegistry — introspection
  # ---------------------------------------------------------------------------

  @scope_resolver_registry @introspection
  Scenario: get_resolvers returns all registered resolvers
    Given a fresh ScopeResolverRegistry
    When I register a null resolver named "r1" with priority 1
    And I register a null resolver named "r2" with priority 2
    Then get_resolvers should return 2 entries
    And get_resolvers should include key "r1"
    And get_resolvers should include key "r2"

  @scope_resolver_registry @introspection
  Scenario: list_resolvers returns entries sorted by priority descending
    Given a fresh ScopeResolverRegistry
    When I register a null resolver named "low_pri" with priority 1
    And I register a null resolver named "high_pri" with priority 9
    And I register a null resolver named "mid_pri" with priority 5
    Then list_resolvers should return 3 entries in priority order
      | name     | priority |
      | high_pri | 9        |
      | mid_pri  | 5        |
      | low_pri  | 1        |

  # ---------------------------------------------------------------------------
  # ScopeResolverRegistry — _discover_resolvers coverage paths
  # ---------------------------------------------------------------------------

  @scope_resolver_registry @discover
  Scenario: Discovery silently ignores entry point load failures
    Given a ScopeResolverRegistry with a failing entry point
    Then the scope resolver registry should be empty

  @scope_resolver_registry @discover
  Scenario: Discovery silently ignores outer entry_points exception
    Given a ScopeResolverRegistry where entry_points raises an exception
    Then the scope resolver registry should be empty

  @scope_resolver_registry @discover
  Scenario: Discovery uses dict-style fallback for older importlib_metadata API
    Given a ScopeResolverRegistry with dict-style entry points returning no scope resolvers
    Then the scope resolver registry should be empty