Feature: Chat with a video's stored transcript
  As a reader whose summary made me want to dig deeper
  I want to ask questions about the video without watching it
  So that I can go further on the ones worth it, without leaving the reader

  # ADR-027. The load-bearing constraint is safety-by-construction: chat runs
  # ONLY against an already-stored transcript (ADR-021) and never fetches captions,
  # never touches the rate gate, never reaches YouTube. Entry is from the summary
  # view of one's OWN video; the conversation is ephemeral (no persisted history).

  Background:
    Given I have a summarized video with a stored transcript

  Scenario: A summary view offers a deeper-dive into the video
    When I view the summary
    Then I see a "dig deeper" affordance that opens a chat about this video
    And it opens the chat in place, below the summary, without leaving the page

  Scenario: The summary and the chat are on one page
    When I open the chat
    Then the summary stays visible alongside the chat
    And I can read the summary while I ask questions

  Scenario: Ask a question answered from the stored transcript
    When I ask a question in the chat
    Then the answer is produced from the stored transcript
    And no caption fetch and no YouTube call occurs

  Scenario: Chat never fetches captions or reaches YouTube
    When I ask a question in the chat
    Then Tapir reads only the stored transcript
    And the caption-fetch and video-fetch paths are never invoked

  Scenario: A video with no stored transcript offers no chat
    Given a video that has no stored transcript
    When I open the chat for it
    Then I am told chat is not available
    And no fetch is attempted and no model is called

  Scenario: The default model is the summary's model and is switchable
    When I open the chat
    Then the model defaults to the model that produced the summary
    And I can switch among the offered chain models

  Scenario: Switching models re-runs against the same transcript
    When I ask a question with a different chain model selected
    Then the chosen model answers
    And it answers against the same stored transcript

  Scenario: The cloud model is hidden when cloud is disabled
    Given the cloud fallback model is disabled
    Then the chat switcher offers only local models

  Scenario: A long transcript is bounded and the chat says so
    Given the stored transcript is longer than the model budget
    When I ask a question
    Then the answer is produced from a bounded portion
    And the chat notes that it worked from a bounded portion

  Scenario: A multi-turn conversation is ephemeral
    When I ask a follow-up question
    Then the prior turn is carried into the answer
    And nothing about the conversation is written to the database

  Scenario: Chat is reachable only from my own summary view
    Given another user has a summarized video with a stored transcript
    When I try to open the chat for their video
    Then I get a not-found response
    And no model is called