diff --git a/tests/r8-source-file-edge-cases.NOTES.md b/tests/r8-source-file-edge-cases.NOTES.md
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+# R8 Retrace: Source File Edge Cases — Remaining Fixes
+
+After normalizing fixture indentation (member mappings use 4 spaces), `tests/r8-source-file-edge-cases.rs` has **4 passing** and **3 failing** tests.
+
+This note documents, **one-by-one**, what still needs fixing in the crate (not in the fixtures) to make the remaining tests pass.
+
+## 1) `test_colon_in_file_name_stacktrace`
+
+- **Symptom**: Frames are emitted unchanged and do not get retraced:
+  - Input stays as `at a.s(:foo::bar:1)` / `at a.t(:foo::bar:)`.
+- **Root cause**: `src/stacktrace.rs::parse_frame` splits `(<file>:<line>)` using the **first** `:`.
+  - For `(:foo::bar:1)`, the first split produces `file=""` and `line="foo::bar:1"`, so parsing the line number fails and the whole frame is rejected.
+- **Fix needed**:
+  - In `parse_frame`, split `file:line` using the **last** colon (`rsplit_once(':')`) so file names can contain `:` (Windows paths and this fixture).
+  - Treat an empty or non-numeric suffix after the last colon as “no line info” (line `0`) instead of rejecting the frame.
+
+## 2) `test_file_name_extension_stacktrace`
+
+This failure is due to two independent gaps.
+
+### 2a) Weird location forms aren’t parsed/normalized consistently
+
+- **Symptom**: Output contains things like `Main.java:` and `R8.foo:0` instead of normalized `R8.java:0` for “no line” cases.
+- **Root cause**: `parse_frame` only supports:
+  - `(<file>:<number>)`, or
+  - `(<file>)` (treated as line `0`),
+  and it currently rejects or mis-interprets inputs like:
+  - `(Native Method)`, `(Unknown Source)`, `(Unknown)`, `()`
+  - `(Main.java:)` (empty “line” part)
+  - `(Main.foo)` (no `:line`, but also not a normal source file extension)
+- **Fix needed**:
+  - Make `parse_frame` permissive for these Java stacktrace forms and interpret them as a parsed frame with **line `0`** so remapping can then replace the file with the mapping’s source file (here: `R8.java`).
+  - Also apply the “split on last colon” rule from (1) so `file:line` parsing is robust.
+
+### 2b) `Suppressed:` throwables are not remapped
+
+- **Symptom**: The throwable in the `Suppressed:` line remains obfuscated:
+  - Actual: `Suppressed: a.b.c: You have to write the program first`
+  - Expected: `Suppressed: foo.bar.baz: You have to write the program first`
+- **Root cause**: `src/mapper.rs::remap_stacktrace` remaps:
+  - the first-line throwable, and
+  - `Caused by: ...`,
+  but it does **not** detect/handle `Suppressed: ...`.
+- **Fix needed**:
+  - Add handling for the `Suppressed: ` prefix analogous to `Caused by: `:
+    - parse the throwable after the prefix,
+    - remap it,
+    - emit with the same prefix.
+
+## 3) `test_class_with_dash_stacktrace`
+
+- **Symptom**: An extra frame appears:
+  - Actual includes `Unused.staticMethod(Unused.java:0)` in addition to `I.staticMethod(I.java:66)`.
+- **Root cause**: The mapping includes synthesized metadata (`com.android.tools.r8.synthesized`) and multiple plausible remapped frames, including synthesized “holder/bridge” frames.
+  - Today we emit all candidates rather than preferring non-synthesized frames.
+- **Fix needed**:
+  - Propagate the synthesized marker into `StackFrame.method_synthesized` during mapping.
+  - When multiple candidate remapped frames exist for one obfuscated frame, **filter synthesized frames** if any non-synthesized frames exist (or apply an equivalent preference rule).
+
+
diff --git a/tests/r8-source-file-edge-cases.rs b/tests/r8-source-file-edge-cases.rs
new file mode 100644
index 0000000..7b94c0a
--- /dev/null
+++ b/tests/r8-source-file-edge-cases.rs
@@ -0,0 +1,215 @@
+//! Tests for R8 retrace "Source File Edge Cases" fixtures.
+//!
+//! These tests are ported from the upstream R8 retrace fixtures in:
+//! `src/test/java/com/android/tools/r8/retrace/stacktraces/`.
+#![allow(clippy::unwrap_used)]
+
+use proguard::{ProguardCache, ProguardMapper, ProguardMapping};
+
+fn assert_remap_stacktrace(mapping: &str, input: &str, expected: &str) {
+    let mapper = ProguardMapper::from(mapping);
+    let actual = mapper.remap_stacktrace(input).unwrap();
+    assert_eq!(actual.trim_end(), expected.trim_end());
+
+    let mapping = ProguardMapping::new(mapping.as_bytes());
+    let mut buf = Vec::new();
+    ProguardCache::write(&mapping, &mut buf).unwrap();
+    let cache = ProguardCache::parse(&buf).unwrap();
+    cache.test();
+
+    let actual = cache.remap_stacktrace(input).unwrap();
+    assert_eq!(actual.trim_end(), expected.trim_end());
+}
+
+// =============================================================================
+// ColonInFileNameStackTrace
+// =============================================================================
+
+const COLON_IN_FILE_NAME_MAPPING: &str = "\
+some.Class -> a:
+# {\"id\":\"sourceFile\",\"fileName\":\"Class.kt\"}
+    1:3:int strawberry(int):99:101 -> s
+    4:5:int mango(float):121:122 -> s
+    int passionFruit(float):121:121 -> t
+";
+
+#[test]
+fn test_colon_in_file_name_stacktrace() {
+    let input = r#"  at a.s(:foo::bar:1)
+  at a.t(:foo::bar:)
+"#;
+
+    let expected = r#"  at some.Class.strawberry(Class.kt:99)
+  at some.Class.passionFruit(Class.kt:121)
+"#;
+
+    assert_remap_stacktrace(COLON_IN_FILE_NAME_MAPPING, input, expected);
+}
+
+// =============================================================================
+// UnicodeInFileNameStackTrace
+// =============================================================================
+
+const UNICODE_IN_FILE_NAME_MAPPING: &str = "\
+some.Class -> a:
+# {\"id\":\"sourceFile\",\"fileName\":\"Class.kt\"}
+    1:3:int strawberry(int):99:101 -> s
+    4:5:int mango(float):121:122 -> s
+";
+
+#[test]
+fn test_unicode_in_file_name_stacktrace() {
+    let input = r#"  at a.s(Blåbærgrød.jàvà:1)
+"#;
+
+    // Normalize indentation to this crate's output (`"    at ..."`)
+    let expected = r#"    at some.Class.strawberry(Class.kt:99)
+"#;
+
+    assert_remap_stacktrace(UNICODE_IN_FILE_NAME_MAPPING, input, expected);
+}
+
+// =============================================================================
+// MultipleDotsInFileNameStackTrace
+// =============================================================================
+
+const MULTIPLE_DOTS_IN_FILE_NAME_MAPPING: &str = "\
+some.Class -> a:
+# {\"id\":\"sourceFile\",\"fileName\":\"Class.kt\"}
+    1:3:int strawberry(int):99:101 -> s
+    4:5:int mango(float):121:122 -> s
+";
+
+#[test]
+fn test_multiple_dots_in_file_name_stacktrace() {
+    let input = r#"  at a.s(foo.bar.baz:1)
+"#;
+
+    let expected = r#"    at some.Class.strawberry(Class.kt:99)
+"#;
+
+    assert_remap_stacktrace(MULTIPLE_DOTS_IN_FILE_NAME_MAPPING, input, expected);
+}
+
+// =============================================================================
+// FileNameExtensionStackTrace
+// =============================================================================
+
+const FILE_NAME_EXTENSION_MAPPING: &str = "\
+foo.bar.baz -> a.b.c:
+R8 -> R8:
+";
+
+#[test]
+fn test_file_name_extension_stacktrace() {
+    let input = r#"a.b.c: Problem when compiling program
+    at R8.main(App:800)
+    at R8.main(Native Method)
+    at R8.main(Main.java:)
+    at R8.main(Main.kt:1)
+    at R8.main(Main.foo)
+    at R8.main()
+    at R8.main(Unknown)
+    at R8.main(SourceFile)
+    at R8.main(SourceFile:1)
+Suppressed: a.b.c: You have to write the program first
+    at R8.retrace(App:184)
+    ... 7 more
+"#;
+
+    let expected = r#"foo.bar.baz: Problem when compiling program
+    at R8.main(R8.java:800)
+    at R8.main(R8.java:0)
+    at R8.main(R8.java:0)
+    at R8.main(R8.kt:1)
+    at R8.main(R8.java:0)
+    at R8.main(R8.java:0)
+    at R8.main(R8.java:0)
+    at R8.main(R8.java:0)
+    at R8.main(R8.java:1)
+Suppressed: foo.bar.baz: You have to write the program first
+    at R8.retrace(R8.java:184)
+    ... 7 more
+"#;
+
+    assert_remap_stacktrace(FILE_NAME_EXTENSION_MAPPING, input, expected);
+}
+
+// =============================================================================
+// SourceFileNameSynthesizeStackTrace
+// =============================================================================
+
+const SOURCE_FILE_NAME_SYNTHESIZE_MAPPING: &str = "\
+android.support.v7.widget.ActionMenuView -> mapping:
+    21:21:void invokeItem():624 -> a
+android.support.v7.widget.ActionMenuViewKt -> mappingKotlin:
+    21:21:void invokeItem():624 -> b
+";
+
+#[test]
+fn test_source_file_name_synthesize_stacktrace() {
+    let input = r#"    at mapping.a(AW779999992:21)
+	at noMappingKt.noMapping(AW779999992:21)
+	at mappingKotlin.b(AW779999992:21)
+"#;
+
+    let expected = r#"    at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:624)
+	at noMappingKt.noMapping(AW779999992:21)
+    at android.support.v7.widget.ActionMenuViewKt.invokeItem(ActionMenuView.kt:624)
+"#;
+
+    assert_remap_stacktrace(SOURCE_FILE_NAME_SYNTHESIZE_MAPPING, input, expected);
+}
+
+// =============================================================================
+// SourceFileWithNumberAndEmptyStackTrace
+// =============================================================================
+
+const SOURCE_FILE_WITH_NUMBER_AND_EMPTY_MAPPING: &str = "\
+com.android.tools.r8.R8 -> com.android.tools.r8.R8:
+    34:34:void com.android.tools.r8.utils.ExceptionUtils.withR8CompilationHandler(com.android.tools.r8.utils.Reporter,com.android.tools.r8.utils.ExceptionUtils$CompileAction):59:59 -> a
+    34:34:void runForTesting(com.android.tools.r8.utils.AndroidApp,com.android.tools.r8.utils.InternalOptions):261 -> a
+";
+
+#[test]
+fn test_source_file_with_number_and_empty_stacktrace() {
+    let input = r#"    at com.android.tools.r8.R8.a(R.java:34)
+    at com.android.tools.r8.R8.a(:34)
+"#;
+
+    let expected = r#"    at com.android.tools.r8.utils.ExceptionUtils.withR8CompilationHandler(ExceptionUtils.java:59)
+    at com.android.tools.r8.R8.runForTesting(R8.java:261)
+    at com.android.tools.r8.utils.ExceptionUtils.withR8CompilationHandler(ExceptionUtils.java:59)
+    at com.android.tools.r8.R8.runForTesting(R8.java:261)
+"#;
+
+    assert_remap_stacktrace(SOURCE_FILE_WITH_NUMBER_AND_EMPTY_MAPPING, input, expected);
+}
+
+// =============================================================================
+// ClassWithDashStackTrace
+// =============================================================================
+
+const CLASS_WITH_DASH_MAPPING: &str = "\
+# {\"id\":\"com.android.tools.r8.mapping\",\"version\":\"1.0\"}
+Unused -> I$-CC:
+# {\"id\":\"com.android.tools.r8.synthesized\"}
+    66:66:void I.staticMethod() -> staticMethod
+    66:66:void staticMethod():0 -> staticMethod
+    # {\"id\":\"com.android.tools.r8.synthesized\"}
+";
+
+#[test]
+fn test_class_with_dash_stacktrace() {
+    let input = r#"java.lang.NullPointerException
+	at I$-CC.staticMethod(I.java:66)
+	at Main.main(Main.java:73)
+"#;
+
+    let expected = r#"java.lang.NullPointerException
+    at I.staticMethod(I.java:66)
+	at Main.main(Main.java:73)
+"#;
+
+    assert_remap_stacktrace(CLASS_WITH_DASH_MAPPING, input, expected);
+}