tune: a progress display for --tune, per-ISA [tuned] fallbacks, and arm64 cpu_supports

CLAUDE.md

@@ -304,7 +304,7 @@ A generic that should accept `array<T>`, `array<array<T>>`, … (any nesting) 
 - **`where` and `shared` are reserved words too** — `where` is the comprehension filter keyword and
   `shared` the module modifier; both are a syntax error as a variable name (`let where = ...`,
   `let shared = ...`). Rename (`sink_pos`, `shared_node`); hit while writing PERF026-028
-- **`label`, `expect`, and `pass` are reserved words** (lexer keywords `DAS_LABEL`/`DAS_EXPECT`/`DAS_PASS` — `pass` is the no-op statement) — using any as a parameter/variable name is a syntax error; rename (`tag`, `want`, `cpass`)
+- **`label`, `expect`, `pass`, and `explicit` are reserved words** (lexer keywords `DAS_LABEL`/`DAS_EXPECT`/`DAS_PASS`/`DAS_EXPLICIT` — `pass` is the no-op statement, `explicit` the generic-parameter modifier you see in `array<T> explicit` signatures) — using any as a parameter/variable name is a syntax error; rename (`tag`, `want`, `cpass`, `declared`)
 - **`range`/`urange`/`range64`/`urange64` are lexer TYPE tokens** (`DAS_TRANGE` etc., like `int`) — unusable as struct-field, parameter, or annotation-argument names (`@range = ...` is a syntax error); the grammar whitelists them back to a plain name only in call position, which is why `range(10)` works. Rename (`rng`, `span`); grammar-verified 2026-07-23
 - **Literal `{`/`}` in string literals must be escaped `\{`/`\}`** — unescaped `{...}` is interpolation. Bites when embedding shader/C source as inline strings. String literals may span multiple lines (raw newlines are legal); probe-verified 2026-07-11
 - String builder requires `unsafe` or `options persistent_heap` if returned

daslib/tty.das

@@ -0,0 +1,51 @@
+options gen2
+options indenting = 4
+options strict_smart_pointers = true
+
+module tty shared public
+
+//! Terminal capability probes — is a stream a real terminal, and how wide is it.
+//!
+//! This is the gate for anything that redraws itself with ``\r``: a progress bar written to a
+//! pipe, a redirect, or a supervising process is garbage in the resulting log. Sniffing ``TERM``
+//! is not enough — it stays set when stdout is redirected. ``daslib/ansi_colors`` handles
+//! styling; this module answers the capability question underneath it.
+
+require fio_core
+
+//! Standard stream numbers, for ``is_stream_terminal``.
+let TTY_STDIN = 0
+let TTY_STDOUT = 1
+let TTY_STDERR = 2
+
+//! Width assumed by ``terminal_columns`` when nothing reports one.
+let TTY_DEFAULT_WIDTH = 80
+
+def is_stream_terminal(fd : int) : bool {
+    //! True when the standard stream `fd` (`TTY_STDIN` / `TTY_STDOUT` / `TTY_STDERR`) is
+    //! attached to a terminal. Any other descriptor is false.
+    return is_terminal(fd)
+}
+
+def is_stdin_terminal() : bool {
+    //! True when standard input is attached to a terminal.
+    return is_terminal(TTY_STDIN)
+}
+
+def is_stdout_terminal() : bool {
+    //! True when standard output is attached to a terminal. This is the gate for a redrawn
+    //! progress display — false under a pipe, a redirect, or a supervising process.
+    return is_terminal(TTY_STDOUT)
+}
+
+def is_stderr_terminal() : bool {
+    //! True when standard error is attached to a terminal.
+    return is_terminal(TTY_STDERR)
+}
+
+def terminal_columns(fallback = TTY_DEFAULT_WIDTH) : int {
+    //! Terminal width in columns, substituting `fallback` when neither the terminal nor
+    //! ``COLUMNS`` reports one. Pass `fallback = 0` for the raw probe.
+    let w = terminal_width()
+    return w > 0 ? w : fallback
+}

doc/reflections/das2rst.das

@@ -27,6 +27,7 @@ require daslib/regex_boost
 require daslib/apply
 require daslib/algorithm
 require daslib/ansi_colors
+require daslib/tty
 require daslib/jobque_boost
 require daslib/jobque_profile
 require daslib/apply_in_context
@@ -220,6 +221,7 @@ def document_module_fio(_root : string) {
         group_by_regex("Directory manipulation", mod, %regex~(dir|dir_rec|mkdir|mkdir_rec|mkdir_result|rmdir|rmdir_rec|rmdir_rec_result|rmdir_result|chdir|getcwd)$%%),
         group_by_regex("Glob and pattern matching", mod, %regex~(match_glob|glob|glob_filtered|is_glob_pattern|expand_glob|parse_file_list)$%%),
         group_by_regex("Filesystem queries", mod, %regex~(temp_directory|temp_directory_result|create_temp_file|create_temp_file_result|create_temp_directory|create_temp_directory_result|disk_space)$%%),
+        group_by_regex("Terminal queries", mod, %regex~(is_terminal|terminal_width)$%%),
         group_by_regex("OS specific routines", mod, %regex~(sleep|exit|system|popen|popen_binary|popen_timeout|spawn_argv|popen_argv|popen_argv_pipe|popen_timed_out|run_and_capture|get_env_variable|set_env_variable|sanitize_command_line|has_env_variable)$%%),
         group_by_regex("Dynamic modules", mod, %regex~(register_dynamic_module|register_native_path)$%%)
     )
@@ -648,6 +650,15 @@ def document_module_ansi_colors(_root : string) {
     document("ANSI terminal color and style helpers", mod, "ansi_colors.rst", groups)
 }
 
+def document_module_tty(_root : string) {
+    var mod = find_module("tty")
+    var groups <- array<DocGroup>(
+        group_by_regex("Terminal detection", mod, %regex~.*(is_stream_terminal|is_stdin_terminal|is_stdout_terminal|is_stderr_terminal)$%%),
+        group_by_regex("Terminal geometry", mod, %regex~.*(terminal_columns)$%%)
+    )
+    document("Terminal capability probes", mod, "tty.rst", groups)
+}
+
 def document_module_algorithm(_root : string) {
     var mod = find_module("algorithm")
     var groups <- array<DocGroup>(
@@ -1839,6 +1850,7 @@ def main {
     // document daslib modules
     document_module_algorithm(root)
     document_module_ansi_colors(root)
+    document_module_tty(root)
     document_module_apply_in_context(root)
     document_module_apply(root)
     document_module_archive(root)

doc/source/stdlib/handmade/function-fio-is_terminal-0x356da75bc2909a8d.rst

@@ -0,0 +1 @@
+Returns true when the standard stream `fd` (0 for input, 1 for output, 2 for error) is attached to a terminal. Any other descriptor, and every stream that is a pipe or a file, returns false.

doc/source/stdlib/handmade/function-fio-terminal_width-0x911587b28bfa73bb.rst

@@ -0,0 +1 @@
+Returns the terminal width in columns, or 0 when nothing reports one — the stream is not a terminal, or the platform query failed. Falls back to the COLUMNS environment variable before giving up.

doc/source/stdlib/handmade/module-tty.rst

@@ -0,0 +1,29 @@
+The TTY module answers whether a stream is attached to a real terminal, and how
+wide that terminal is.
+
+This is the gate for anything that redraws itself with a carriage return: a
+progress bar written to a pipe, a redirect, or a supervising process is garbage
+in the resulting log. Checking ``TERM`` is not a substitute — it stays set when
+standard output is redirected. ``daslib/ansi_colors`` handles styling; this
+module answers the capability question underneath it.
+
+All functions and symbols are in "tty" module, use require to get access to it.
+
+.. code-block:: das
+
+    require daslib/tty
+
+Example:
+
+.. code-block:: das
+
+    require daslib/tty
+
+    [export]
+    def main() {
+        if (is_stdout_terminal()) {
+            print("drawing a {terminal_columns()}-column progress bar\n")
+        } else {
+            print("output is captured — emitting plain lines instead\n")
+        }
+    }

doc/source/stdlib/introduction.rst

@@ -163,6 +163,7 @@ Developer tools
 ---------------
 
 * :doc:`ansi_colors <generated/ansi_colors>` — ANSI terminal color escape sequences
+* :doc:`tty <generated/tty>` — terminal capability probes (is it a terminal, how wide)
 * :doc:`command_line <generated/command_line>` — command-line argument parsing helpers
 * :doc:`das_source_formatter <generated/das_source_formatter>` — daslang source code formatter
 * :doc:`das_source_formatter_fio <generated/das_source_formatter_fio>` — file-based source code formatting

doc/source/stdlib/sec_io.rst

@@ -17,6 +17,7 @@ File I/O, networking, URI parsing, terminal output, and binary serialization.
    generated/uriparser.rst
    generated/uriparser_boost.rst
    generated/ansi_colors.rst
+   generated/tty.rst
    generated/archive.rst
    generated/command_line.rst
    generated/logger.rst

history/README.md

@@ -98,3 +98,4 @@ listed in the log below — search it first when hunting for a doc.
 - 2026-07-25 `modules/dasLLAMA/benchmarks/prefill_metal_chase.das` -> `history/dasLLAMA/benchmarks/prefill_metal_chase.das` - Metal prefill chase instrument (arc shipped)
 - 2026-07-25 `modules/dasLLAMA/benchmarks/bench_metal_framing.das` -> `history/dasLLAMA/benchmarks/bench_metal_framing.das` - Metal framing-overhead bench (arc shipped)
 - 2026-07-25 `modules/dasLLAMA/benchmarks/gguf_perf.das` -> `history/dasLLAMA/benchmarks/gguf_perf.das` - gguf load-time bench (the .dlim rail made it moot)
+- 2026-07-27 `modules/dasLLVM/TUNE_PROGRESS_PLAN.md` -> `history/compiler/TUNE_PROGRESS_UX.md` - tune progress-display design (events + single renderer; arc shipped, operative content in skills/tune.md)