Reject special files without blocking, cap the properties payload at 1 MiB before allocation, and verify descriptor extent and the selected name. Preserve Latin-1 data, selected symlinks, physical filesystem facts, completed observations and exact failed-close ownership.
Reuse the stable bounded reader for profile artifacts and consolidate Ghidra file failure projection. Distinguish missing-at-open from disappearance or read failure, and attribute typed prerequisite failures at the consuming operation.
Validation: 384 focused tests across 14 files, 42 seed/extension controls, 32 final metadata/profile/CLI controls, check:fast and docs:check. Controlled macOS file/process fixtures; no real Ghidra/JVM or Windows/Linux lifecycle verification.
Bounded FIFO reproduction: baseline direct and public doctor required external cleanup around 2.2s; candidate returned independently around 0.4/0.57s, all fixture groups verified empty. Warm normal doctor baseline/candidate: elapsed 1.211/1.230s, CPU 1.239/1.247s, sampled family RSS 524/524MB, reply tokens 3116/3116. No performance improvement claimed; true cold and whole-agent costs unmeasured.
Refs #4672