[jesse23]

Problem

Pasting multi-line text into pi running inside herdr inside webtty submitted the first line and queued every other line as a separate message.

A joining client (reloaded tab, second tab, or a 4003 reconnect) rebuilds its terminal from the scrollback ring: the last 256 Ki characters of output. herdr writes ESC[?2004h (bracketed paste) once when it attaches and then redraws its whole screen (~35 KB each), so the sequence leaves the ring quickly. The new tab has bracketed paste off, so libghostty-vt pastes raw text with each newline sent as \r (Enter).

Fix

• src/server/sessions/input-modes.ts (InputModes) follows DECSET/DECRST through the PTY output for the DEC modes that change what the client sends: 1, 9, 1000–1007, 1015, 1016, 2004, 2031, 2048. RIS clears them all and DECSTR clears mode 1. A sequence split across chunks is carried over to the next chunk. A chunk with no ESC returns at once.
• Session.ensurePty sends a joining client one DECSET for the modes that are on, followed by the scrollback, in the same message. The DECSET goes first because the ring can end in the middle of a sequence.
• ADR 070 records the decision; the webtty and architecture SPECs are updated.

Testing

• Unit tests: input-modes.test.ts plus a session test that checks the restore when the ring has already been trimmed. All 3,104 tests pass; lint and coverage checks pass.
• End to end, run on separate ports (2398 and 2399) with a separate HOME and a headless Chrome. The test shell sets mode 2004, writes 400 KB, then records its raw input. After a reload, a three-line paste arrived as:
  • before (1.x, port 2398): line one^Mline two^Mline three
  • after (this branch, port 2399): ^[[200~line one\nline two\nline three^[[201~

Not covered

The kitty keyboard protocol's flags (CSI > … u, a stack kept per screen) are not followed; they behave the same as before this change.

[jesse23]

Checked end to end on the real stack: dev webtty (bun run webtty, port 2399, isolated HOME) → herdr (separate session, isolated state) → pi 1.3.0, driven from headless Chrome.

1. Started pi in a herdr pane.
2. Resized the page 32 times so herdr redrew its whole screen. A raw client then got a replay whose history no longer contains ESC[?2004h. The new restore prefix was ESC[?1000;1002;1003;1004;1006;1015;2004;2031h (herdr's bracketed paste, mouse, focus and color-scheme modes).
3. Reloaded the tab and pasted line one\nline two\nline three. All three lines landed in pi's editor as one paste and nothing was submitted.