fix(web): a draft thread's panel says the Environment browser comes with its first message (#53)

[immakermatty]

Status: ready for review

Why

#53, found on the F47 canary and seen again by Matěj on 2026-10-12 in 0.0.45-preview.20261012.1. On a new thread before its first message, the right panel showed upstream's empty state, with Browser "Only available in the desktop app.", although the Environment has a browser.

A draft is no thread of the server yet. Its tab stream answered 404, which an EventSource never retries.

While fixing it, a second gap showed up. ChatView's promotion is data-driven: the draft keeps its thread ref when its first message makes it a server thread. So the failed stream was never reopened, and Nová karta did not appear on the new thread until a reload or a navigation away and back.

Matěj chose the smaller variant of #53 (2026-10-12): keep upstream's empty state on a draft, and say in one line why the browser is not there yet.

What changes

• ChatView.tsx (the one hook call): it passes draft: !isServerThread to useLazurioThreadTabs.
• Overlay (LazurioEnvironmentBrowser.tsx, threadTabs.ts, LazurioNewTab.tsx):
  • a draft opens no tab stream, so it gets no 404, and the store records the draft in view;
  • when the thread becomes the server's, the stream opens (the effect depends on the flag), and Nová karta follows the first snapshot as on any thread.
• Empty state (RightPanelTabs.tsx):
  • where the shell defines <lazurio-new-tab> and a draft is in view, the empty state shows one line under the list: "Prohlížeč Environmentu bude k dispozici po první zprávě." (English: "The Environment browser comes with the first message.");
  • the same text replaces the Browser row's desktop-only reason.
  • Where the server already said of another thread that this Environment has no browser, upstream's line stays.
• What does not change:
  • the desktop app, mobile and non-Lazurio pages;
  • the "+" menu when a draft has other surfaces open, which keeps upstream's Browser reason (documented).
• Contract test: it pins the two seams.
• Runbook: it records the behaviour, the seams and the pre-release browser check.

Verification

• vp test run src/lazurio (web): 72 passed, including the new cases:
  • a draft opens no stream, and its promotion opens it;
  • the line shows on a draft with the shell's element;
  • the line is absent without the element, or where the server said the Environment has no browser.
• node --test scripts/lazurio-release-contract.test.mjs: 22 passed.
• vp fmt --check: clean. Web typecheck: clean.
• In the browser (root 0178), on the canary after the preview release: a new thread shows the line before its first message, and Nová karta after it without a reload.

Release

Goes into the next T3 preview together with the Environment-name and panel tuning from Matěj's 2026-10-12 review, then stable 0.0.45-lazurio.8 after his check.

🤖 Generated with Claude Code

[agentrozjedemeai]

@immakermatty APPROVED — exact head 06d3aed. Ověřil jsem přechod konceptu na serverové vlákno při stejném refu: draft neotevírá EventSource, změna příznaku znovu spouští efekt a po cleanupu otevírá stream. Věta v prázdném panelu je omezená na shell s Novou kartou a bez dřívějšího unavailable snapshotu; desktop a mobilní cesta zůstávají mimo overlay. Švy v ChatView/RightPanelTabs a kontrakt testu odpovídají diffu. Lokálně: 22/22 release-contract testů, git diff --check čistý; webové testy/typecheck/fmt jsou doložené zeleným CI na tomto headu, lokální web suite jsem bez závislostí nespouštěl. Vlákna 0, CI green, main c2dd835, mergeable. Schválení neznamená vydání stable: prohlížečový canary check a release gate zůstávají Matějovi.

[immakermatty]

Merged (rebase) at 830f4a4. The local worktree DEV-6646-draft-thread-note was removed after verifying all three commits are on main and the remote branch holds the same head (06d3aed).