Feature: Session Domain Model
  As a developer
  I want session domain models for conversation management
  So that sessions can be created, tracked, and exported via CLI

  # ---- Session Creation ----

  Scenario: Create a session with valid ULID
    When I create a session with a valid ULID
    Then the session model should be created
    And the session model session_id should be a valid ULID

  Scenario: Create a session with actor name
    When I create a session with actor name "local/orchestrator"
    Then the session model should be created
    And the session model actor_name should be "local/orchestrator"

  Scenario: Create a session without actor name
    When I create a session without actor name
    Then the session model should be created
    And the session model actor_name should be empty

  Scenario: Session has default namespace local
    When I create a session with a valid ULID
    Then the session model namespace should be "local"

  # ---- Session ID Validation ----

  Scenario: Session rejects invalid ULID format
    When I try to create a session with invalid ID "not-a-ulid"
    Then a session model validation error should be raised

  # ---- Actor Name Validation ----

  Scenario: Session rejects invalid actor name format
    When I try to create a session with invalid actor name "badformat"
    Then a session model validation error should be raised

  Scenario: Session accepts None actor name
    When I create a session without actor name
    Then the session model should be created

  # ---- Message Append with Auto-sequencing ----

  Scenario: Append a user message to session
    Given a session with no messages
    When I append a user message "Hello"
    Then the session model should have 1 message
    And the session last message content should be "Hello"
    And the session last message role should be "user"
    And the session last message sequence should be 0

  Scenario: Append multiple messages with auto-sequencing
    Given a session with no messages
    When I append a user message "Hello"
    And I append an assistant message "Hi there"
    Then the session model should have 2 messages
    And the session last message sequence should be 1

  # ---- Message Role Validation ----

  Scenario: Tool message requires tool_call_id
    When I try to create a tool message without tool_call_id
    Then a session model validation error should be raised
    And the session model error should mention "tool_call_id"

  Scenario: Tool message with tool_call_id is valid
    When I create a tool message with tool_call_id "call_123"
    Then the session message should be created
    And the session message tool_call_id should be "call_123"

  Scenario: User message does not require tool_call_id
    When I create a user message "Hello"
    Then the session message should be created

  # ---- Content Validation ----

  Scenario: Message rejects whitespace-only content
    When I try to create a message with whitespace-only content
    Then a session model validation error should be raised
    And the session model error should mention "whitespace"

  Scenario: Message rejects empty content
    When I try to create a message with empty content
    Then a session model validation error should be raised

  # ---- Message Ordering ----

  Scenario: Messages must be ordered by sequence
    When I try to create a session with out-of-order messages
    Then a session model validation error should be raised
    And the session model error should mention "ordered by sequence"

  # ---- Plan Linking ----

  Scenario: Link a plan to session
    Given a session with no messages
    When I link plan "01ARZ3NDEKTSV4RRFFQ69G5FAV" to the session
    Then the session should have 1 linked plan

  Scenario: Plan linking deduplicates
    Given a session with no messages
    When I link plan "01ARZ3NDEKTSV4RRFFQ69G5FAV" to the session
    And I link plan "01ARZ3NDEKTSV4RRFFQ69G5FAV" to the session
    Then the session should have 1 linked plan

  Scenario: Link multiple plans
    Given a session with no messages
    When I link plan "01ARZ3NDEKTSV4RRFFQ69G5FAV" to the session
    And I link plan "01BX5ZZKBKACTAV9WEVGEMMVRY" to the session
    Then the session should have 2 linked plans

  # ---- Token Usage Tracking ----

  Scenario: Default token usage is zero
    When I create a session with a valid ULID
    Then the session token usage input_tokens should be 0
    And the session token usage output_tokens should be 0
    And the session token usage estimated_cost should be 0.0

  Scenario: Token usage with values
    When I create a session with token usage 100 input 50 output 0.05 cost
    Then the session token usage input_tokens should be 100
    And the session token usage output_tokens should be 50
    And the session token usage estimated_cost should be 0.05

  Scenario: Token usage rejects negative values
    When I try to create token usage with negative input tokens
    Then a session model validation error should be raised

  # ---- Export Dict ----

  Scenario: Export dict contains checksum
    Given a session with some messages
    When I export the session
    Then the export dict should have key "checksum"
    And the export dict should have key "schema_version"
    And the export dict should have key "messages"
    And the export dict should have key "session_id"

  Scenario: Export dict round-trip preserves data
    Given a session with some messages
    When I export the session
    Then the export dict messages count should match session message count

  # ---- CLI Dict ----

  Scenario: CLI dict has required fields
    Given a session with some messages
    When I get the session CLI dict
    Then the session cli dict should have key "session_id"
    And the session cli dict should have key "message_count"
    And the session cli dict should have key "created_at"
    And the session cli dict should have key "updated_at"
    And the session cli dict should have key "token_usage"
    And the session cli dict should have key "namespace"

  Scenario: CLI dict includes recent messages
    Given a session with some messages
    When I get the session CLI dict
    Then the session cli dict should have key "recent_messages"

  Scenario: CLI dict includes actor when set
    When I create a session with actor name "local/orchestrator"
    And I get the session CLI dict
    Then the session cli dict should have key "actor_name"

  Scenario: CLI dict includes automation level when set
    Given a session with automation level "full_automation"
    When I get the session CLI dict
    Then the session cli dict should have key "automation_level"

  # ---- Empty Session Properties ----

  Scenario: Empty session has zero message count
    Given a session with no messages
    Then the session message count should be 0
    And the session is_empty should be true
    And the session last_message should be none

  # ---- get_messages with limit/offset ----

  Scenario: get_messages with no limit returns all
    Given a session with 5 messages
    When I get messages with no limit
    Then I should get 5 messages

  Scenario: get_messages with limit
    Given a session with 5 messages
    When I get messages with limit 3
    Then I should get 3 messages

  Scenario: get_messages with offset
    Given a session with 5 messages
    When I get messages with offset 2
    Then I should get 3 messages

  Scenario: get_messages with limit and offset
    Given a session with 5 messages
    When I get messages with limit 2 and offset 1
    Then I should get 2 messages

  # ---- Session Error Types ----

  Scenario: SessionServiceError is base error
    Then SessionServiceError should be an Exception subclass

  Scenario: SessionNotFoundError inherits from SessionServiceError
    Then SessionNotFoundError should be a SessionServiceError subclass

  Scenario: SessionExportError inherits from SessionServiceError
    Then SessionExportError should be a SessionServiceError subclass

  Scenario: SessionImportError inherits from SessionServiceError
    Then SessionImportError should be a SessionServiceError subclass

  # ---- MessageRole enum ----

  Scenario: MessageRole has expected values
    Then the MessageRole enum should have values "user,assistant,system,tool"

  # ---- Session metadata ----

  Scenario: Session supports metadata
    When I create a session with metadata
    Then the session metadata should contain key "env"

  # ---- Export dict linked plans ----

  Scenario: Export dict includes linked plan IDs
    Given a session with no messages
    When I link plan "01ARZ3NDEKTSV4RRFFQ69G5FAV" to the session
    And I export the session
    Then the export dict should have key "linked_plan_ids"

  # ---- Robot Smoke Alignment: Serialization Order ----

  Scenario: Export dict keys are in expected serialization order
    Given a session with some messages
    When I export the session
    Then the export dict keys should be in expected serialization order

  Scenario: Export dict messages are ordered by sequence
    Given a session with some messages
    When I export the session
    Then the export dict messages should be ordered by sequence