[Feature]: Add outline review and refinement step before content generation

[nkmohit]

Problem or Motivation

After outline generation, the app waits 800ms and then immediately starts scene content generation by calling /api/generate/scene-content with no user confirmation step. Users currently can’t remove unwanted scenes, reorder items, or adjust titles before the expensive generation runs.

This is also different from #68 (post-generation editing) because this feature enables controlled pre-generation, saving unnecessary calls for scenes the user doesn’t want.

Proposed Solution

Two-phase approach:

Short term (UI wiring):

• Wire up the existing OutlinesEditor component (components/generation/outlines-editor.tsx) into the outline->content flow in app/generation-preview/page.tsx.
• After /api/generate/scene-outlines-stream finishes streaming, pause on the outline step and render OutlinesEditor.
• Only proceed to content generation after the user clicks a confirm action, using the (possibly edited) outlines.

Long term (conversation loop):

• Add a conversational refinement loop so users can provide natural-language feedback (e.g., “remove the quiz scenes”, “add a section on positional encoding”, “make it more beginner friendly”).
• The AI regenerates/refines the outline based on the original requirement + prior outline + user feedback.
• Repeat until the user confirms, then start scene content generation.

Alternatives Considered

• Do post-generation editing only (but is less efficient because content generation already happened).
• Full regeneration from scratch (works but slower and more costly than targeted outline refinement).

Area

Classroom generation

Additional Context

• There is an OutlinesEditor component in components/generation/outlines-editor.tsx that appears to be planned for this use case but is currently unused.
• This change would give curators control before expensive generation and supports both manual editing now and AI-assisted iteration later.

[nkmohit]

following up from this comment in #150 - wyuc mentioned that a mandatory confirmation step added friction in earlier testing, which makes sense for casual users who just want to generate quickly.
one possible middle ground: an optional toggle in the generation toolbar (similar to how Image/Video/TTS/ASR are surfaced) that is off by default. casual users see no change, but course curators or users who want to review the outline before committing can enable it. might be worth exploring if the friction concern was mainly about it being mandatory rather than the feature itself.

[nkmohit]

drafted a minimal implementation in #198 if it's useful as a reference. it's opt-in via a toolbar toggle (off by default) so the default flow is completely unchanged. happy to keep it as a draft until there's appetite to revisit.