Add a config-backed incremental_reindex policy with default fast so full and moderate indexes rebuild atomically instead of entering the current disk incremental path, which still performs full-graph quality work and can be slower than a clean rebuild. Keep always for benchmarking and off for deterministic full rebuilds.
Harden the existing incremental path around allocation failures before mutation: classify, changed-file list, graph buffer creation, changed-path set, and deleted-path copies now fail closed or preserve existing nodes rather than dereferencing NULL or recording corrupt path arrays.
Reuse the existing pipeline nanosecond constant for file-hash mtimes and keep the dedicated incremental suite opted into incremental_reindex=always so its canaries continue exercising the legacy disk incremental implementation.
Validation: make -f Makefile.cbm build/c/test-runner cbm; CBM_ONLY_SUITE=pipeline build/c/test-runner: 212 passed; CBM_ONLY_SUITE=cli build/c/test-runner: 102 passed; CBM_ONLY_SUITE=mcp build/c/test-runner: 113 passed; CBM_ONLY_SUITE=tool_consolidation build/c/test-runner: 94 passed; git diff --check.
Signed-off-by: Andrew Hundt <ATHundt@gmail.com>
Andrew Hundt
a7e80d8a61