feat(compress): move cdict stream init policy into Rust

Move ZSTD_initCStream_usingCDict_advanced's reset, pledge, frame-parameter,
and CDict callback ordering into the Rust projection. Keep private CCtx and
CDict mutations in C callbacks and pass frame parameters as scalars across the
ABI boundary.

Test Plan:
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo test --manifest-path rust/Cargo.toml init_cstream_using_cdict_advanced -- --test-threads=1
- ulimit -v 41943040; make -B -C programs -j1 zstd
- git diff --cached --check

rust/src/zstd_compress.rs

@@ -857,6 +857,98 @@ pub unsafe extern "C" fn ZSTD_rust_resetCStream(
     0
 }
 
+type InitCStreamUsingCDictAdvancedResetFn = unsafe extern "C" fn(*mut c_void) -> usize;
+type InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn =
+    unsafe extern "C" fn(*mut c_void, u64) -> usize;
+type InitCStreamUsingCDictAdvancedSetFrameParamsFn =
+    unsafe extern "C" fn(*mut c_void, c_uint, c_uint, c_uint);
+type InitCStreamUsingCDictAdvancedRefCDictFn =
+    unsafe extern "C" fn(*mut c_void, *const c_void) -> usize;
+
+/// Explicit projection for `ZSTD_initCStream_usingCDict_advanced`.
+///
+/// Rust owns the public wrapper's callback order and error propagation while
+/// C retains the private context and dictionary/parameter mutations.
+#[repr(C)]
+pub struct ZSTD_rust_initCStreamUsingCDictAdvancedState {
+    callback_context: *mut c_void,
+    reset_session: InitCStreamUsingCDictAdvancedResetFn,
+    set_pledged_src_size: InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn,
+    set_frame_params: InitCStreamUsingCDictAdvancedSetFrameParamsFn,
+    ref_cdict: InitCStreamUsingCDictAdvancedRefCDictFn,
+}
+
+const _: () = {
+    assert!(size_of::<InitCStreamUsingCDictAdvancedResetFn>() == size_of::<usize>());
+    assert!(size_of::<InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn>() == size_of::<usize>());
+    assert!(size_of::<InitCStreamUsingCDictAdvancedSetFrameParamsFn>() == size_of::<usize>());
+    assert!(size_of::<InitCStreamUsingCDictAdvancedRefCDictFn>() == size_of::<usize>());
+    assert!(
+        offset_of!(
+            ZSTD_rust_initCStreamUsingCDictAdvancedState,
+            callback_context
+        ) == 0
+    );
+    assert!(
+        offset_of!(ZSTD_rust_initCStreamUsingCDictAdvancedState, reset_session)
+            == size_of::<usize>()
+    );
+    assert!(
+        offset_of!(
+            ZSTD_rust_initCStreamUsingCDictAdvancedState,
+            set_pledged_src_size
+        ) == 2 * size_of::<usize>()
+    );
+    assert!(
+        offset_of!(
+            ZSTD_rust_initCStreamUsingCDictAdvancedState,
+            set_frame_params
+        ) == 3 * size_of::<usize>()
+    );
+    assert!(
+        offset_of!(ZSTD_rust_initCStreamUsingCDictAdvancedState, ref_cdict)
+            == 4 * size_of::<usize>()
+    );
+    assert!(size_of::<ZSTD_rust_initCStreamUsingCDictAdvancedState>() == 5 * size_of::<usize>());
+};
+
+#[no_mangle]
+pub unsafe extern "C" fn ZSTD_rust_initCStreamUsingCDictAdvanced(
+    state: *const ZSTD_rust_initCStreamUsingCDictAdvancedState,
+    pledged_src_size: u64,
+    content_size_flag: c_uint,
+    checksum_flag: c_uint,
+    no_dict_id_flag: c_uint,
+    cdict: *const c_void,
+) -> usize {
+    if state.is_null() {
+        return ERROR(ZstdErrorCode::Generic);
+    }
+    let state = unsafe { &*state };
+
+    let result = unsafe { (state.reset_session)(state.callback_context) };
+    if ERR_isError(result) {
+        return result;
+    }
+    let result = unsafe { (state.set_pledged_src_size)(state.callback_context, pledged_src_size) };
+    if ERR_isError(result) {
+        return result;
+    }
+    unsafe {
+        (state.set_frame_params)(
+            state.callback_context,
+            content_size_flag,
+            checksum_flag,
+            no_dict_id_flag,
+        )
+    };
+    let result = unsafe { (state.ref_cdict)(state.callback_context, cdict) };
+    if ERR_isError(result) {
+        return result;
+    }
+    0
+}
+
 type CompressStreamBlockFn =
     unsafe extern "C" fn(*mut c_void, *mut c_void, usize, *const c_void, usize) -> usize;
 type CompressStreamResetFn = unsafe extern "C" fn(*mut c_void) -> usize;
@@ -8701,6 +8793,135 @@ mod tests {
         assert_eq!(context.pledged_src_size, 123);
     }
 
+    #[derive(Default)]
+    struct InitCStreamUsingCDictAdvancedTestContext {
+        events: Vec<&'static str>,
+        reset_result: usize,
+        pledged_result: usize,
+        ref_result: usize,
+        pledged_src_size: u64,
+        frame_params: [c_uint; 3],
+        cdict: *const c_void,
+    }
+
+    unsafe fn init_cstream_using_cdict_advanced_test_context(
+        context: *mut c_void,
+    ) -> &'static mut InitCStreamUsingCDictAdvancedTestContext {
+        unsafe { &mut *context.cast::<InitCStreamUsingCDictAdvancedTestContext>() }
+    }
+
+    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_reset(
+        context: *mut c_void,
+    ) -> usize {
+        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
+        context.events.push("reset");
+        context.reset_result
+    }
+
+    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_set_pledged(
+        context: *mut c_void,
+        pledged_src_size: u64,
+    ) -> usize {
+        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
+        context.events.push("pledged");
+        context.pledged_src_size = pledged_src_size;
+        context.pledged_result
+    }
+
+    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_set_frame_params(
+        context: *mut c_void,
+        content_size_flag: c_uint,
+        checksum_flag: c_uint,
+        no_dict_id_flag: c_uint,
+    ) {
+        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
+        context.events.push("frame");
+        context.frame_params = [content_size_flag, checksum_flag, no_dict_id_flag];
+    }
+
+    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_ref_cdict(
+        context: *mut c_void,
+        cdict: *const c_void,
+    ) -> usize {
+        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
+        context.events.push("ref-cdict");
+        context.cdict = cdict;
+        context.ref_result
+    }
+
+    fn init_cstream_using_cdict_advanced_test_state(
+        context: &mut InitCStreamUsingCDictAdvancedTestContext,
+    ) -> ZSTD_rust_initCStreamUsingCDictAdvancedState {
+        ZSTD_rust_initCStreamUsingCDictAdvancedState {
+            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
+            reset_session: init_cstream_using_cdict_advanced_test_reset,
+            set_pledged_src_size: init_cstream_using_cdict_advanced_test_set_pledged,
+            set_frame_params: init_cstream_using_cdict_advanced_test_set_frame_params,
+            ref_cdict: init_cstream_using_cdict_advanced_test_ref_cdict,
+        }
+    }
+
+    #[test]
+    fn init_cstream_using_cdict_advanced_preserves_order_and_scalars() {
+        let cdict = ptr::dangling::<c_void>();
+        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
+        let state = init_cstream_using_cdict_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, cdict) };
+
+        assert_eq!(result, 0);
+        assert_eq!(context.events, ["reset", "pledged", "frame", "ref-cdict"]);
+        assert_eq!(context.pledged_src_size, 77);
+        assert_eq!(context.frame_params, [1, 2, 3]);
+        assert_eq!(context.cdict, cdict);
+    }
+
+    #[test]
+    fn init_cstream_using_cdict_advanced_stops_after_reset_error() {
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_using_cdict_advanced_test_state(&mut context);
+
+        let result =
+            unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, ptr::null()) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
+        assert_eq!(context.events, ["reset"]);
+    }
+
+    #[test]
+    fn init_cstream_using_cdict_advanced_stops_after_pledged_size_error() {
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            pledged_result: ERROR(ZstdErrorCode::StageWrong),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_using_cdict_advanced_test_state(&mut context);
+
+        let result =
+            unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, ptr::null()) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
+        assert_eq!(context.events, ["reset", "pledged"]);
+    }
+
+    #[test]
+    fn init_cstream_using_cdict_advanced_propagates_ref_error_after_frame_params() {
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            ref_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_using_cdict_advanced_test_state(&mut context);
+
+        let result =
+            unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, ptr::null()) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
+        assert_eq!(context.events, ["reset", "pledged", "frame", "ref-cdict"]);
+        assert_eq!(context.frame_params, [1, 2, 3]);
+    }
+
     #[test]
     fn pledged_src_size_writes_the_init_stage_value_plus_one() {
         let mut pledged_src_size_plus_one = 0;