[reilly1993]

Problem

Some human-solvable puzzles were reported as requiring search because the logical solver stopped before Alternating Inference Chain deductions. The reported 18:09 puzzle contains such a route, despite being solvable without guessing.

Solution

• Add deterministic Alternating Inference Chain detection using valid strong and weak candidate links.
• Restrict eliminations to candidates that see both valid chain endpoints.
• Run simpler Turbot Fish techniques before AIC so puzzles keep the lowest honest classification.
• Integrate AIC into grading, bounded logical analysis and progressive hints.
• Classify AIC as Master, add a plain-language explanation and render its two chain groups distinctly on the board.
• Advance logical-analysis metadata to bounded-logical-v3 so older analyses are recomputed.
• Add frozen regressions for the reported 18:09 position, invalid-link rejection, deterministic solving and no-search classification.

Verification

• Rebased onto the latest main; Turbot Fish is inherited from the merged Add Skyscraper and 2-String Kite solver paths #23 instead of duplicated.
• 197 Bun tests pass.
• TypeScript typecheck passes.
• Biome passes across src.
• Production Vite/PWA build and git diff --check pass.
• A prior randomized audit compared 2,000 puzzles with the known backtracking solution and found no AIC solution mismatch; a further 1,000-puzzle audit found no elimination of a solution candidate.
• The reported 18:09 puzzle now solves logically with AIC and reaches the known solution without Backtracking.