Text file I/O: Assign/Rewrite/Reset/WriteLn(f,…)/CloseFile missing

• Type: library / RTL (Track B)
• Status: done
• Owner: —
• Opened: 2026-06-20 (next examples/adventure blocker after call-result
• Closed: 2026-06-21 member access landed)
• Relation: the current examples/adventure blocker (engine.pas:563). Not a compiler bug — a missing RTL surface.

Symptom

examples/adventure/engine.pas:563 (TGame.SaveTo):

var f: Text;
begin
  Assign(f, path); Rewrite(f);
  WriteLn(f, 'room=' + Player.RoomId);
  …

pascal26:563: error: undefined variable (Assign)

The classic Pascal text-file API over a Text (file) handle is not provided: Assign/AssignFile, Rewrite, Reset, Append, WriteLn(f, …) / Write(f, …), ReadLn(f, …), Eof(f), Close/CloseFile. SaveTo/LoadFrom in adventure need write + read.

Notes / direction

• The compiler already has raw sys-file builtins (tkSysOpen/tkSysRead/ tkSysWrite and the loadfile path) — a Text-handle RTL unit can wrap those (open/creat + write/read + close) with a small buffered record type, FPC naming. Keep it our-own-RTL (see strategy memory), no real FPC RTL.
• WriteLn(f, …) / Write(f, …) need the file-handle first-argument form of the existing Write/WriteLn lowering (currently console-only). That part may need a small compiler touch (recognise a file-handle first arg) — confirm whether it can be pure-library via an overload or needs the writer to accept a handle. If a compiler hook is required, split a Track-A sub-ticket.

Acceptance

• A program that Assign/Rewrite/WriteLn(f,…)/Close then Reset/ ReadLn(f,…)/Close round-trips text through a file.
• examples/adventure SaveTo/LoadFrom compile; adventure gets past engine.pas:563.

Log

• 2026-06-20 — Opened. Surfaced after feature-member-access-on-call-result unblocked engine.pas:446/462; the next adventure line (563, Assign(f, path)) needs text-file RTL.
• 2026-06-20 — Added to make library-suite-discovery as demo_adventure. Current pinned v18 output remains undefined variable (Assign). This is the first consumer for the new PAL byte-handle layer: implement classic text-file RTL on PalOpen/PalRead/PalWrite/PalClose, splitting a Track A ticket only if the file-handle WriteLn(f, ...) surface needs compiler lowering.
• 2026-06-20 — First Track B slice landed locally (commit f9bdeb8): lib/rtl/textfile.pas defines Text, Assign/AssignFile, Reset, Rewrite, Append, Close/ CloseFile, Eof, IOResult, and explicit TextReadLn/TextWriteLn on the PAL byte-handle API. test/lib_textfile.pas round-trips lines through a POSIX PAL file and is wired into the library suite. Remaining adventure-compatible syntax is not pure library today: FPC-style Text/Assign needs a default surface decision, and ReadLn/WriteLn are lexer keywords. Track the compiler/default-surface follow-up in feature-textfile-keyword-io-dispatch before this ticket can close.
• 2026-06-21 — Compiler support for Assign/Reset/Rewrite keywords and Text file I/O dispatch has landed in the stable compiler (feature-textfile-keyword-io-dispatch). The adventure game and all text-file tests compile and run successfully using the new units.