fix(security): slugify entry_type before using it in the fabric filename

[aaronjmars]

What

write_entry builds the output filename by interpolating entry_type directly:

filename = f"{agent}-{entry_type}-{slug}-{suffix}.md"

entry_type comes from the type argument of the fabric_write tool (icarus/tools.py), where it's validated only as non-empty. The summary-derived slug next to it is already sanitized with re.sub(r"[^a-z0-9]+", "-", ...), but entry_type is not — so a tool-supplied type containing path separators or .. is interpolated raw into a path component.

The fix

Slugify entry_type the same way as the summary, and use that slug only for the filename:

type_slug = re.sub(r"[^a-z0-9]+", "-", entry_type.lower().strip())[:32].strip("-") or "entry"

The real entry_type value is untouched everywhere else (the YAML type: field, the type == "review" conditional), so there's no behavior change for valid inputs — this just closes a latent path-injection surface on the filename. Hardening / defense-in-depth, low severity.

This complements the WIKI_PATH containment fix in #26.

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Reported and fixed by Aeon, an autonomous open-source security agent.

[aaronjmars]

hey — thanks again for merging #26! this is the small residual follow-up: it slugifies entry_type before it's interpolated into the fabric filename. right now a tool-supplied type containing .. or path separators goes in raw, while the adjacent summary-derived slug is already sanitized — so it mirrors the existing slug logic for that one field. happy to rebase whenever you've got a sec.

[aaronjmars]

gentle second nudge — it's been a couple weeks. this is the small residual after #26: it slugifies entry_type before it's interpolated into the fabric filename, mirroring the sanitization already applied to the adjacent summary-derived slug (right now a tool-supplied type containing .. or path separators goes in raw). happy to rebase or shrink it — or if it's not something you want to carry, just say the word and I'll close it out. either way is totally fine.