feat: Dispatch UI — full-screen post overlay + cover image prompt generator

[melagiri]

Feature Summary

Two enhancements to the Dispatch UI that improve the post preview and drafting experience.

Scope tags: VISUAL, API_CHANGE

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Enhancement 1 — Full-Screen Post Overlay

Replace the in-drawer post preview with a full-screen overlay that opens immediately after generation.

What changes:

• New PostOverlay.tsx component: shadcn Dialog with full-screen override classes (max-w-none w-screen h-screen rounded-none p-0)
• DispatchDrawer.tsx becomes config-only (no longer shows post preview inline)
• After generation, overlay opens automatically with the result
• Drawer stays open behind overlay so selection state is preserved
• Escape key + X button close the overlay
• Closing overlay discards result (no draft saving — intentional)
• Drawer footer shows "View post" + "Regenerate" buttons when a result exists

Files modified:

• dashboard/src/components/dispatch/PostOverlay.tsx (new)
• dashboard/src/components/dispatch/DispatchDrawer.tsx (config-only refactor)

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Enhancement 2 — On-Demand Cover Image Prompt Generator

A new button in the overlay that generates a text prompt suitable for image generation tools (Midjourney, DALL-E, Gemini Imagen).

What changes:

• New endpoint: POST /api/dispatch/image-prompt
  • Input: { title, tags, tldr, format } — title+tldr+tags only (no body)
  • Output: { prompt: string, model: string, tokensUsed: { input, output } }
  • Temperature: 0.85, responseFormat: 'text'
  • Single attempt, no retry
  • parseImagePromptOutput strips meta-commentary, trims, validates non-empty
• New CoverImagePromptSection.tsx component: "Get cover image prompt" button (Sparkles icon) → mutation → read-only Textarea + Copy button + Regenerate link
• Lives inside PostOverlay below PostPreview

System prompt: Instructs LLM to act as a visual art director producing a single paragraph (50-75 words) — concrete visual scene, style, 2-3 color palette, mood/lighting, no text/logos, tool-agnostic.

Files modified/created:

• server/src/llm/dispatch-prompts.ts — add buildImagePromptSystemPrompt, buildImagePromptContext, parseImagePromptOutput
• server/src/routes/dispatch.ts — add POST /image-prompt handler
• cli/src/types.ts — add DispatchImagePromptRequest, DispatchImagePromptResponse
• dashboard/src/lib/api.ts — add generateDispatchImagePrompt
• dashboard/src/components/dispatch/CoverImagePromptSection.tsx (new)
• dashboard/src/components/dispatch/PostOverlay.tsx (new — embeds PostPreview + CoverImagePromptSection)

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Implementation Sequence (TDD)

1. Types in cli/src/types.ts
2. Tests for 3 new dispatch-prompts.ts functions (red)
3. Implement buildImagePromptSystemPrompt, buildImagePromptContext, parseImagePromptOutput (green)
4. Tests for POST /image-prompt endpoint (red)
5. Add POST /image-prompt handler to dispatch.ts (green), pnpm test in server/
6. Add generateDispatchImagePrompt + types to dashboard/src/lib/api.ts
7. Build CoverImagePromptSection.tsx
8. Build PostOverlay.tsx (embeds PostPreview + CoverImagePromptSection)
9. Modify DispatchDrawer.tsx (config-only, overlay sibling)
10. pnpm build from root, run dashboard, verify full flow

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Scope Boundary (explicitly out of scope)

• Inline post editing
• Draft saving
• Publish integrations
• Actual image rendering
• Model-tier routing
• Streaming image prompt
• Prompt history

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Acceptance Criteria

Full-screen overlay:

• Post overlay opens immediately after generation, covers full viewport
• Drawer remains open behind overlay (selection state preserved)
• Escape key and X button close overlay
• Closing overlay discards result (no stale state on reopen)
• "View post" + "Regenerate" buttons appear in drawer footer when result exists

Cover image prompt:

• POST /api/dispatch/image-prompt returns { prompt, model, tokensUsed } for valid input
• parseImagePromptOutput strips meta-commentary, trims, rejects empty string
• buildImagePromptContext uses title+tldr+tags only (no body)
• "Get cover image prompt" button triggers mutation, shows loading state
• Result renders in read-only Textarea with Copy + Regenerate controls
• pnpm build from repo root: zero errors
• pnpm test in server/: all tests pass

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T-Shirt Size: M

Design locked pre-implementation by TA + LLM Expert consultation. No architectural decisions pending.

Branch: feature/dispatch-ui-full-screen-overlay-post-preview-on-de
Worktree: /Users/melagiri/Workspace/codeInsights/code-insights-dispatch-ui-full-screen-overlay-post-preview-on-de/

[melagiri]

Completed in PR #299

Triple-layer review converged — 0 FIX NOW items remaining.

What shipped:

• Full-screen PostOverlay (shadcn Dialog, w-screen h-screen, ARIA-compliant)
• CoverImagePromptSection with 4-state useMutation UI (idle/loading/error/success), Copy + Regenerate
• POST /api/dispatch/image-prompt endpoint (temp 0.85, responseFormat text, preamble-stripping parser)
• DispatchDrawer refactored to config-only with overlay sibling

Review fixes applied:

• U+2019 curly apostrophe added to PREAMBLE_PATTERNS
• FORMAT_TONE_LABELS corrected (linkedin → 'accessible')
• PostOverlay X button WCAG 2.4.7 focus ring
• CoverImagePromptSection Regenerate button type + focus-visible ring

Gate results: pnpm build PASS, pnpm test PASS (1162 tests)

Full review: #299 (comment)

Ready for founder merge.