Inclusion Criteria:
* Female patients aged 18 to 75 years.
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.
* Histologically confirmed unilateral primary invasive breast cancer, staged as at least cT2 or cN1 (i.e., AJCC 8th edition stage II-III), and M0.
* Pathologically confirmed HER2-positive breast cancer, defined as HER2 IHC 3+, or IHC 2+ with positive in situ hybridization (ISH).
* At least one measurable lesion according to RECIST version 1.1.
* Adequate major organ function, meeting all of the following criteria: Hematology criteria (without blood transfusion or hematopoietic growth factor support within 7 days before screening): hemoglobin (HB) \>= 90 g/L; absolute neutrophil count (ANC) \>= 1.5 x 10\^9/L; platelet count (PLT) \>= 75 x 10\^9/L.
* Biochemistry criteria: total bilirubin (TBIL) \<= 1.5 x upper limit of normal (ULN); alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \<= 3 x ULN; serum creatinine (Cr) \<= 1.5 x ULN; endogenous creatinine clearance \> 50 mL/min (Cockcroft-Gault formula).
* 12-lead electrocardiogram: Fridericia-corrected QT interval (QTcF) \< 470 msec; echocardiography: left ventricular ejection fraction (LVEF) \>= 55%.
* Women of childbearing potential must use at least one medically accepted contraceptive method during study treatment and for at least 3 months after the last dose of study drug.
* Subjects must voluntarily participate in the study, sign the informed consent form, demonstrate good compliance, and cooperate with follow-up.
Exclusion Criteria:
* Bilateral breast cancer, inflammatory breast cancer, or clinically stage IV (metastatic) breast cancer.
* Any prior systemic targeted therapy, chemotherapy, endocrine therapy, biologic therapy, radiotherapy, or immunotherapy for any reason.
* Any of the following comorbidities, medical histories, or treatment histories:
* Known or suspected interstitial pneumonitis; or moderate to severe pulmonary disease severely affecting respiratory function, such as severe asthma or severe chronic obstructive pulmonary disease (COPD).
* Serious cardiovascular or cerebrovascular disease, including but not limited to New York Heart Association (NYHA) class II or higher heart failure (including class II), myocardial infarction or cerebrovascular accident (including cerebral ischemia or symptomatic cerebral infarction) within 3 months before first dosing, or persistent arrhythmia of grade \>= 2.
* Severe systemic infection (e.g., requiring intravenous antibiotics, antifungal agents, or antiviral drugs according to clinical practice standards), or unexplained fever \> 38.5 degrees C during screening or before first dosing.
* Clinically significant bleeding symptoms within 1 month before signing informed consent, or definite bleeding tendency, such as gastrointestinal bleeding, hemorrhagic gastric ulcer, or baseline fecal occult blood of ++ or above.
* Known hypersensitivity or intolerance to the investigational medicinal products or their excipients.
* Any other malignancy within the previous 5 years, except cured cervical carcinoma in situ or non-melanoma skin cancer.
* Pregnancy or lactation, or refusal by women of childbearing potential to use appropriate contraception during the trial.
* Participation in another clinical trial within 30 days before the first dose of study drug.
* Any other condition that, in the investigator's judgment, makes the patient unsuitable for participation in the study.
