arXiv:2610.34141v1 Announce Type: new Abstract: Legacy C codebases remain central to system software and performance-critical infrastructure, but their weak memory safety imposes security and maintenance risks. Recent C-to-Rust translation systems, including LLM-based translators, make automated migration increasingly feasible, yet they still struggle to recover repository-level intent, avoid raw pointers and unsafe constructs, maintain cross-file interfaces, and repair compilation and validation failures efficiently. We propose SpeC2Rust, a specification-driven pipeline for repository-level C-to-Rust translation. It has three stages: (1) Project-Intent Structuring, which decomposes a C repository into semantically coherent modules and generates persistent repository- and module-level specifications; (2) Spec-Guided Generation, which translates each Rust module against these specifications with a live symbol registry to preserve cross-file consistency; and (3) Layered-Feedback Repair, which batches repairs and injects only failure-relevant diagnostics, specification context, and source evidence for efficient compilation and test-driven correction. We evaluate SpeC2Rust on eight repository-level C projects. It generates Rust projects that compile and pass the original end-to-end tests, with no raw-pointer declarations, raw-pointer dereferences, or unsafe lines. On projects shared with an LLM-based baseline, SpeC2Rust reduces cost by 66.1% and input-token usage by 84.7%.