This diachronic constraint-based analysis details shifting reflexes in Proto-French (PF) and early Old French (OF) (approximately 2nd-12th centuries) towards the repair of underlying obstruent-nasal clusters, especially where the obstruent is coronal, as well as phonotactically dispreferred /tl, dl/. In earlier PF, deletion and gemination prevail, with gemination broadening scope from flat-sonority clusters to some obstruent-sonorant clusters, including /dl/ and variably obstruent-nasal. Late PF /dn/ assibilates to [zn], avoiding a suboptimal syllable-contact sonority contour, with the end result of both processes finalizing a broader coda obstruent ban before OF. Early OF ecclesiastic loanwords from Latin re-introduce underlying medial obstruent-nasal and /tl, dl/ clusters, with the cluster-final sonorant undergoing the novel repair of rhotacization (/n/ or /l/ " [r]), representing an extension of manner change seen in earlier spirantization and assibilation in the native lexicon. The unified optimality-theoretic analysis identifies and argues for a multi-stage shift in the prioritization of constraints governing the intersecting deletion, gemination, spirantization, assibilation, and rhotacization processes, and their interaction with syllabification, sonority, and phonotactics.