fix(chat): copy what the bubble shows (#269) + keep a sent message pinned

[kfaracik]

Why

Two independent chat bugs.

1. Copying a reply with <think> tags (#269). The Copy button put message.content on the clipboard verbatim — including the <think>…</think> block and the [n] citation markers that are hidden on screen. Pasting that back rendered a nearly empty user bubble: parseThinkingContent ran for every role, and the user branch rendered only the text before <think>, dropping the block and everything after </think>. The DB row was always intact — the loss was purely visual, but the model did receive the raw markup.

2. A sent message sometimes wasn't pinned. From the second message on, the new message occasionally stayed where it was appended instead of moving below the header, forcing a manual scroll. The pin was a single scrollToEnd fired from onContentSizeChange, but the list's maximum offset keeps moving for a few hundred milliseconds after that:

• blankSpace is applied as the scroll view's bottom contentInset (ScrollViewWithBottomPadding in keyboard-controller), and Reanimated commits it on the UI thread a frame or more after JS sets it;
• the inset is recomputed again once the new user row and the assistant placeholder report their heights;
• the keyboard dismissed by the send itself animates out for ~250 ms, and keyboard-controller drives its own per-frame scrollTo the whole time.

Whichever lands last wins, so a lone scroll aims at a stale end and falls short. The first message in a chat was masked by the initial-scroll retry loop; later ones had no safety net. Independently, the Android keyboard-dismiss re-snap was gated on wasAtBottomDuringKeyboard, so sending after scrolling up skipped the last correction.

What changed

• utils/thinking.ts — one home for the think parser, previously duplicated in MessageItem and messageSources; also normalises an orphan </think>.
• utils/messageText.ts — visibleMessageText() decides what Copy puts on the clipboard: think blocks out, citation markers out when the reply is grounded in sources, and a reply that is only reasoning falls back to that reasoning instead of an empty string.
• User bubbles keep every word — only the think markers are dropped — so pasted markup can no longer swallow the bubble. New chat titles are built from the marker-free text.
• useScrollSettler re-asserts the scroll position across the settling window (animated while the send transition runs, instant afterwards). recomputeBlankSpace re-snaps whenever it moves the inset, a drag cancels the pin so the user is never fought, and a send in flight now outranks the keyboard-dismiss gate. A 300 ms fallback runs the pin even if onContentSizeChange never arrives.

Test plan

• yarn test — 772 passing, incl. new __tests__/messageText.test.ts (15) and __tests__/useScrollSettler.test.ts (8, fake timers: correction order and animation mode, cancel-on-drag, restart mid-window, unmount cleanup).
• yarn lint, yarn format:check, npx tsc --noEmit clean for the touched files.
• Not verified on a device: the settler's root cause is derived from the app code and the keyboard-controller sources, not from a reproduced failure on hardware. Worth a manual pass — send several messages in a row, including from a scrolled-up position and with a multi-line input.

Closes #269

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
private-mind	Error		Jul 31, 2026 11:30pm