penguin-harness/changelog/0.2.0/2026-08-02-file-tool-missing-path-diagnostics.md

File tools diagnose missing paths instead of implying absolute paths are rejected

read_file / edit_file accepted absolute paths all along, but their "File not found" message mentioned only workspace-relative resolution — so a genuinely missing file (typically a dropped agent_state/ segment) read as "absolute paths are unsupported", and the model retried path forms instead of questioning the path (#138).

Details

• Both tools now state that absolute paths are supported and append a diagnostic: the deepest existing ancestor directory, the first missing segment, and the ancestor's entries ranked by name similarity to the missing one (capped at 8, directories marked with a trailing slash) — for the reported case the hint names agent_state/ directly.
• ENOTDIR (a path segment that is a file, not a directory) gets the same diagnosis instead of a raw errno message.
• The agent-creation Skill now spells out that AGENTS.md lives under agent_state/, not at the agent directory root — the likely source of the dropped segment (skill version 7).