fix(a11y): distinguish unavailable read-back from rejected writes

CHANGELOG.md

@@ -23,6 +23,7 @@ internal refactors, CI, or test-only changes.
 - `Document` accessibility role: a browser page or embedded web view (AT-SPI `document web`/`document frame`, `AXWebArea`, Android `WebView`, UIA `Document` from a web engine) now reads as a `Document` whose children are the page's elements, on Linux, Windows, macOS and Android.
 
 ### Fixed
+- `glass_set_value` no longer reports that a desktop accessibility write "did not take" when the element exposes a writable value but no readable value for confirmation. Linux, macOS and Windows now report the write as unconfirmed and steer the caller to re-snapshot instead of retrying a write that may already have landed.
 - A web view whose content the platform has not published is disclosed in the snapshot instead of arriving as an indistinguishable empty group: a childless `Document` is named by id and bounds and steers to a re-snapshot before pixels, while a placeholder the app published for content it withheld steers straight to pixels.
 - On Linux, `glass_set_value` now confirms a write actually landed instead of trusting the AT-SPI toolkit's own acknowledgment of it, the way the Windows and macOS readers already did: it reads the element back (polling briefly, since the toolkit applies the write on a later main-loop pass), and an element that acknowledges a write without applying it — as web content can — now reports that instead of a silent false success.
 - On Linux, the container of an `<iframe>` inside a browser page no longer reads as a `Window`: AT-SPI's `internal frame`, which the web engines publish for an embedded frame and no desktop toolkit uses, now maps to `Group`, so a `role:"Window"` selector matches the app's real windows again instead of frames inside a page. The nested `Document` inside such a frame is unchanged.

crates/glass-a11y-linux/src/reader.rs

@@ -338,13 +338,18 @@ fn write_verdict(
     observed: Option<&str>,
 ) -> GlassError {
     match observed {
+        None => GlassError::AxWriteUnconfirmed(
+            id,
+            "the element exposes a writable value but no readable value was available after the write"
+                .into(),
+        ),
         Some(seen) if write_took_no_effect(seen, before) => GlassError::value_not_applied_because(
             id,
             requested,
             Some(seen),
             ACKNOWLEDGED_NOT_APPLIED,
         ),
-        seen => GlassError::value_not_applied(id, requested, seen),
+        Some(seen) => GlassError::value_not_applied(id, requested, Some(seen)),
     }
 }
 
@@ -930,8 +935,8 @@ mod tests {
         );
         let unread = write_verdict(3, "typed", Some("old"), None);
         assert!(
-            matches!(unread, GlassError::AxValueNotApplied { why: None, .. }),
-            "a read-back that failed is no evidence about the write; got: {unread:?}"
+            matches!(unread, GlassError::AxWriteUnconfirmed(3, _)),
+            "a read-back that failed cannot prove the write was rejected; got: {unread:?}"
         );
     }
 

crates/glass-a11y-macos/src/reader.rs

@@ -156,6 +156,11 @@ impl Accessibility for MacosA11y {
                 // A read that failed, or one showing a value the element reformatted, is not
                 // evidence of a projection that accepted the write and kept its value.
                 return Err(match after.as_deref() {
+                    None => GlassError::AxWriteUnconfirmed(
+                        target.id.0,
+                        "the element exposes a writable value but no readable value was available after the write"
+                            .into(),
+                    ),
                     Some(seen) if write_took_no_effect(seen, before.as_deref()) => {
                         GlassError::value_not_applied_because(
                             target.id.0,
@@ -164,7 +169,9 @@ impl Accessibility for MacosA11y {
                             READ_ONLY_PROJECTION,
                         )
                     }
-                    seen => GlassError::value_not_applied(target.id.0, text, seen),
+                    Some(seen) => {
+                        GlassError::value_not_applied(target.id.0, text, Some(seen))
+                    }
                 });
             }
             std::thread::sleep(Duration::from_millis(SET_VALUE_POLL_MS));

crates/glass-a11y-windows/src/reader.rs

@@ -410,6 +410,11 @@ fn run_set_value(ctx: &AxContext, target: &AxTarget, text: &str) -> Result<()> {
             // A read that failed, or one showing a value the element reformatted, is not evidence
             // of a projection that accepted the write and kept its value.
             return Err(match after.as_deref() {
+                None => GlassError::AxWriteUnconfirmed(
+                    target.id.0,
+                    "the element exposes a writable value but no readable value was available after the write"
+                        .into(),
+                ),
                 Some(seen) if write_took_no_effect(seen, before.as_deref()) => {
                     GlassError::value_not_applied_because(
                         target.id.0,
@@ -418,7 +423,7 @@ fn run_set_value(ctx: &AxContext, target: &AxTarget, text: &str) -> Result<()> {
                         READ_ONLY_PROJECTION,
                     )
                 }
-                seen => GlassError::value_not_applied(target.id.0, text, seen),
+                Some(seen) => GlassError::value_not_applied(target.id.0, text, Some(seen)),
             });
         }
         std::thread::sleep(Duration::from_millis(VERIFY_POLL_MS));