nx_diskfree.nx

nx_diskfree.nx -- THE DISK AXIS, made callable (2026-08-28). WHY THIS EXISTS. On 2026-08-28 a 100%-FULL DISK truncated a sibling seat's MEMORY.md to 0 bytes: open(path,"w") truncates BEFORE it writes, so a full volume does not refuse a write, it DESTROYS the file. Nothing in the estate saw it coming. nx_resmon is "the resource axis nx_health lacks" -- but only for MEMORY and SWAP; a search for the disk primitive returned matches=0 for BOTH sys_statfs and statvfs with corpus_complete=1, and nx_res_census records the same absence in its own header. THE CAPABILITY WAS DARK, NOT MISSING. nx_system_triage.tr_free_gb has read filesystem space since 2026-06-10 -- inside an _hdl_build organ that is NOT REGISTERED, so nx_job_run refuses it as "not an unpinned GREEN tool" and no caller in the estate can reach it. ★A CAPABILITY THAT EXISTS IN ONE UNREACHABLE ORGAN IS INDISTINGUISHABLE FROM ONE NOBODY BUILT -- and its absence is only discovered by the incident it would have prevented. This organ is the reachable form. The arithmetic lives in nx_syscalls (sys_fs_used_permil / sys_fs_avail_bytes) so nx_resmon can compose the SAME ruler rather than growing a second one. THE THIRD STATE IS LOAD-BEARING. statfs can fail (bad path, unmounted, permission) and a volume can report zero blocks. Both return STATFS_ERR and this organ prints UNMEASURABLE with exit 3 -- it never prints 0 permil used, because "I could not look" and "the disk is empty" must never share a representation, and 0-used is the most flattering possible lie. license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0