[Juliusolsson05]

Fixes the never-ending "remote/mobile send doesn't work" bug (Claude session … did not confirm pasted prompt before submit (timeout)), root-caused with a real-claude PTY harness rather than guessed.

Root cause (verified, not assumed)

Claude's TUI reflects a committed bracketed paste two ways, by size:

• COLLAPSE → [Pasted text #N] placeholder — only big pastes (single-line >800 chars, multiline ≥4 lines).
• INLINE → raw text, no placeholder — everything smaller.

The runtime delivery path (deliverClaudePrompt) waited for the placeholder only (awaitPastePlaceholder). So every short/inlined paste timed out at 2000ms, Enter was withheld, and the prompt stuck in the composer. This hits every short remote prompt — and every dictated prompt, since the <stt>…</stt> wrapper adds newlines and forces the paste route.

It's a drift bug: the desktop composer already confirmed on placeholder OR inline-tail (claudePaste.ts), but that robust detector was never ported to the runtime path.

Measured against real claude (harness in tmp/paste-repro/):

paste	collapse?	old (placeholder-only)	fix (placeholder-or-inline)
single 120ch	inlined	⏱ timeout → stuck	✅ inline @22ms
multiline 2-line	inlined	⏱ timeout → stuck	✅ inline @24ms
dictated <stt> short	inlined	⏱ timeout → stuck	✅ inline @11ms
single 2000ch	collapsed	✅ placeholder	✅ placeholder

The fix

• New shared detector @shared/claude/pasteConfirm — placeholder-count-increase or the paste's normalized 24-char tail newly appearing, against a baseline captured before the paste (the baseline also makes a second paste immune to the first's stale [Pasted text #1]).
• deliverClaudePrompt reads the live screen via a new AgentSession.snapshotScreen (Claude already implements it) — app-only, no submodule change.
• claudePaste.ts now imports the shared detector (byte-identical logic; the battle-scarred timing constants untouched). Duplicated CLAUDE_PASTE_THRESHOLD / isPasteLike collapse to one source, so the two paths can't drift again — which is exactly why this bug existed.

Verification

• tsc -b tsconfig.node.json clean, tsc --noEmit -p tsconfig.web.json clean.
• promptDelivery.test.ts updated to the snapshotScreen mechanism: 6/6 pass, pinning the inline-tail path, the stale-placeholder sequence guard, and Enter-withheld-on-timeout.
• End-to-end against real claude: the actual shared pollPasteAbsorbed resolves absorbed for every dead-zone case (short single-line, short multiline, dictated <stt>) — the exact prompts that used to hang.

Independent of PR #497 (mobile UI); branched off clean main.

🤖 Generated with Claude Code