Delta Command: conversational UI

[nfaggian]

Reworks the AI surface so it reads as a modern conversational interface (Claude, ChatGPT, Cursor Chat, Perplexity) rather than a dashboard with a one-shot "Generate" button.

What changed

Backend

• POST /api/chat accepts a full { messages: [{role, content}] } history and returns the next assistant reply. The system prompt embeds a summary of the live database on every turn — the client never sends state.
• POST /api/briefing is preserved as a canned first-turn wrapper. Both endpoints share a common call_llm(messages) under the hood.
• New ChatRequest / ChatTurn Pydantic models; build_context broadened to include the top-N active opportunities and available engineers so replies can name specifics.
• Tests cover 400/503/success paths for /api/chat, including forwarded-history assertions.

Frontend

• New /chat route as the primary AI surface:
  • Empty-state hero — "What do you need to know?" + four starter prompt tiles
  • Full-height message thread; user bubbles right, assistant left with a Δ mark; MarkdownLite for bold / italic / code / bullets
  • Client-side character-reveal animation with a blinking accent caret at the tip (abortable via Stop)
  • Three-dot typing indicator during the "Analyzing pipeline…" phase
  • Multi-line composer with ⌘⏎ / ⏎ submit, Shift+⏎ newline, auto-grow to ~8 rows, disabled-until-content Send button
  • Copy button on assistant replies, "New chat" reset in the top bar
  • ?prompt=<id> deep-link auto-submits the first turn
• Sidebar: Chat promoted to the first nav item with an accent icon + AI badge; a divider separates it from the data-first nav.
• Dashboard: standalone ExecutiveBriefingPanel replaced by AskDeltaCallout, which presents Delta plus three deep-linked starter prompts. Deleted the panel component.
• New Tailwind keyframes: typing-dot, caret-blink, message-in (fade + lift).
• READMEs updated for the new endpoint and surface.

Design principles applied

1. Chat is the primary primitive. The composer is always ready; no modal.
2. Streaming reveal. Even without SSE, client-side reveal makes replies feel alive.
3. Grounded outputs. Every turn re-embeds live data; the assistant cites specific names, percentages, and clients.
4. Minimal chrome. Sidebar + slim top bar + centered thread + fixed composer, nothing else.
5. Deep links from data surfaces. The dashboard becomes an entry point to the chat, not a competing AI surface.

Verification

• next build clean; new chat bundle is 6.35 kB / 122 kB First Load JS
• tsc --noEmit clean
• 16 / 16 backend tests pass, including the three new /api/chat tests
• Playwright screenshots at 2× DPI:

Empty state

Chat empty state

Streaming reveal (caret visible after "capacity):")

Chat streaming

Complete reply

Chat answered

Composer with follow-up drafted

Chat follow-up input

Dashboard callout (deep-links into /chat?prompt=…)

Dashboard with Ask Delta callout

Stacking

Stacked on cursor/ui-precision-535c (PR #11) → cursor/llm-briefing-535c (PR #9). All roll up to the future nfaggian/delta-tools main.

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