Hair extension practice rarely fails in a single dramatic way. It fails gradually when the cumulative load on natural hair exceeds its structural reserve, when an attachment zone absorbs repeated tension it was not assessed to sustain, or when a client's actual maintenance behavior falls short of what the installation required. This article develops a literature-based algorithm for gradual hair extensions that treats the procedure as a staged adaptation process rather than a one-time intervention. The study draws on 20 verified English-language sources covering hair and scalp diagnostics, hair camouflage, scalp reactions, traction-related damage, and material exposure. It also references the Hair Biomechanical Tolerance Dataset (Cowan Y, 2026), a synthetic illustrative dataset of 108 hypothetical archetypes with rule-generated action directives. Three patterns from this model informed the algorithm. First, scalp condition was encoded as an absolute procedural gate: all archetypes with active erythema or pre-traction markers were assigned refusal, regardless of hair thickness, density, or zone. Second, staged extension is exclusively a Supportive and Conditional zone procedure: none of the 24 Staged Extension profiles is located in the high-risk marginal zone. Third, aftercare compliance reduces safe wear duration by 1.3 to 1.7 weeks across all scalp zones, making it a planning variable rather than post-procedural advice. On this basis, the article proposes a Gradual Hair Extension Algorithm with five decision blocks: structural diagnosis, zonal tolerance assessment, aftercare capacity assessment, phased load planning, and follow-up correction logic. Graduality is not a stylistic preference. It is a principle of biological proportionality.