libghostty: add configurable mode defaults, remove mode_set/get (ghostty-org#13661)

ABI BREAKING: This removes `ghostty_terminal_mode_get` and `_mode_set`.
We can now represent these operations completely with standard
`ghostty_terminal_get` and `ghostty_terminal_set`, which makes it much
more flexible to preserve ABI in the future.

This is all centered around a new `GhosttyTerminalModeConfig` structure
that is an in or out parameter depending on use case.

This also adds a new `GHOSTTY_TERMINAL_OPT_MODE_DEFAULT` option that can
be used to set the _default_ value of mode that happens when a RIS event
(full reset) is sent. Note that not all modes are configurable because
some are set based on live terminal state and aren't modes in and of
themselves.

## Why Delete Functions? Why Not Add?

Once tagged, the goal of `libghostty-vt` is to remain HIGHLY ABI
compatible. We are striving for top tier ABI compatibility similar to
legendary C libraries. That means we need to be highly confident in our
API shapes: functions, structs, etc. and using shapes that we can retain
ABI compatibility even as we add features. Every function is a risk. By
pushing stuff into our `_get/_set` patterns, its easier to maintain ABI
compatibility.

Author: mitchellh

include/ghostty/vt/terminal.h

@@ -695,6 +695,24 @@ typedef void (*GhosttyTerminalWritePtyFn)(GhosttyTerminal terminal,
 typedef GhosttyString (*GhosttyTerminalXtversionFn)(GhosttyTerminal terminal,
                                                      void* userdata);
 
+/**
+ * A terminal mode and boolean value used for mode configuration and queries.
+ *
+ * For GHOSTTY_TERMINAL_DATA_MODE, initialize `mode` before calling
+ * ghostty_terminal_get(). On success, `value` contains the current mode value.
+ *
+ * This struct has a frozen layout and will not gain fields in future versions.
+ *
+ * @ingroup terminal
+ */
+typedef struct {
+  /** Mode to configure or query. */
+  GhosttyMode mode;
+
+  /** Value to set, or the current value returned by a query. */
+  bool value;
+} GhosttyTerminalModeConfig;
+
 /**
  * Terminal option identifiers.
  *
@@ -1060,6 +1078,31 @@ typedef enum GHOSTTY_ENUM_TYPED {
    * Input type: bool*
    */
   GHOSTTY_TERMINAL_OPT_TITLE_REPORT = 32,
+
+  /**
+   * Set the reset default for a terminal mode.
+   *
+   * This unconditionally updates both the current value and the value restored
+   * by a full terminal reset (RIS).
+   *
+   * Some recognized modes represent transitions or mirror additional terminal
+   * state and cannot safely be configured as reset defaults. Those modes return
+   * GHOSTTY_INVALID_VALUE. A NULL value pointer also returns
+   * GHOSTTY_INVALID_VALUE.
+   *
+   * Input type: GhosttyTerminalModeConfig*
+   */
+  GHOSTTY_TERMINAL_OPT_MODE_DEFAULT = 33,
+
+  /**
+   * Set the current value of a terminal mode.
+   *
+   * This does not change the value restored by a full terminal reset (RIS).
+   * A NULL value pointer or unknown mode returns GHOSTTY_INVALID_VALUE.
+   *
+   * Input type: GhosttyTerminalModeConfig*
+   */
+  GHOSTTY_TERMINAL_OPT_MODE = 34,
   GHOSTTY_TERMINAL_OPT_MAX_VALUE = GHOSTTY_ENUM_MAX_VALUE,
 } GhosttyTerminalOption;
 
@@ -1420,6 +1463,17 @@ typedef enum GHOSTTY_ENUM_TYPED {
    * Output type: size_t *
    */
   GHOSTTY_TERMINAL_DATA_CONTINUATION_MAX_BYTES = 36,
+
+  /**
+   * Get the current value of a terminal mode.
+   *
+   * The caller must initialize the `mode` field. On success, the `value` field
+   * is updated with the current value. A NULL pointer or unknown mode returns
+   * GHOSTTY_INVALID_VALUE.
+   *
+   * Input/output type: GhosttyTerminalModeConfig *
+   */
+  GHOSTTY_TERMINAL_DATA_MODE = 37,
   GHOSTTY_TERMINAL_DATA_MAX_VALUE = GHOSTTY_ENUM_MAX_VALUE,
 } GhosttyTerminalData;
 
@@ -1709,41 +1763,6 @@ GHOSTTY_API GhosttyResult ghostty_terminal_compress(
     GhosttyTerminalCompressionMode mode,
     GhosttyTerminalCompressionResult* out_result);
 
-/**
- * Get the current value of a terminal mode.
- *
- * Returns the value of the mode identified by the given mode.
- *
- * @param terminal The terminal handle (NULL returns GHOSTTY_INVALID_VALUE)
- * @param mode The mode identifying the mode to query
- * @param[out] out_value On success, set to true if the mode is set, false
- *             if it is reset
- * @return GHOSTTY_SUCCESS on success, GHOSTTY_INVALID_VALUE if the terminal
- *         is NULL or the mode does not correspond to a known mode
- *
- * @ingroup terminal
- */
-GHOSTTY_API GhosttyResult ghostty_terminal_mode_get(GhosttyTerminal terminal,
-                                        GhosttyMode mode,
-                                        bool* out_value);
-
-/**
- * Set the value of a terminal mode.
- *
- * Sets the mode identified by the given mode to the specified value.
- *
- * @param terminal The terminal handle (NULL returns GHOSTTY_INVALID_VALUE)
- * @param mode The mode identifying the mode to set
- * @param value true to set the mode, false to reset it
- * @return GHOSTTY_SUCCESS on success, GHOSTTY_INVALID_VALUE if the terminal
- *         is NULL or the mode does not correspond to a known mode
- *
- * @ingroup terminal
- */
-GHOSTTY_API GhosttyResult ghostty_terminal_mode_set(GhosttyTerminal terminal,
-                                         GhosttyMode mode,
-                                         bool value);
-
 /**
  * Get data from a terminal instance.
  *

src/lib_vt.zig

@@ -284,8 +284,6 @@ comptime {
         @export(&c.terminal_scroll_viewport, .{ .name = "ghostty_terminal_scroll_viewport" });
         @export(&c.terminal_compression_activity, .{ .name = "ghostty_terminal_compression_activity" });
         @export(&c.terminal_compress, .{ .name = "ghostty_terminal_compress" });
-        @export(&c.terminal_mode_get, .{ .name = "ghostty_terminal_mode_get" });
-        @export(&c.terminal_mode_set, .{ .name = "ghostty_terminal_mode_set" });
         @export(&c.terminal_get, .{ .name = "ghostty_terminal_get" });
         @export(&c.terminal_get_multi, .{ .name = "ghostty_terminal_get_multi" });
         @export(&c.terminal_continuation_write, .{ .name = "ghostty_terminal_continuation_write" });

src/terminal/c/main.zig

@@ -187,8 +187,6 @@ pub const terminal_vt_write = terminal.vt_write;
 pub const terminal_scroll_viewport = terminal.scroll_viewport;
 pub const terminal_compression_activity = terminal.compression_activity;
 pub const terminal_compress = terminal.compress;
-pub const terminal_mode_get = terminal.mode_get;
-pub const terminal_mode_set = terminal.mode_set;
 pub const terminal_get = terminal.get;
 pub const terminal_get_multi = terminal.get_multi;
 pub const terminal_continuation_write = terminal.continuation_write;