docs: legibility note — limitations verified from the tree, nothing existing modified

[SuperInstance]

What this is

A read-only legibility pass. No existing file is modified — this PR only adds
LEGIBILITY.md, and it is trivially deletable. Close it and nothing else changes.

Why

A census of 100 fleet repos (SuperInstance/quilt-research-canons/projects/fleet-legend/)
graded every repo against five obligations. This one already passes entry (L1, L2); it
fails the two that only cost something once a reader is already inside:

• L4 — what this does NOT do. Missing in 55 of 100 repos.
• L5 — what to do when it fails. Missing in 59 of 100 repos.

What is in here, and where each line came from

5 finding(s), each read out of the repository and each carrying its evidence. Nothing
is inferred from the README, because the README is the thing being fixed.

finding	evidence
A CI workflow exists (2 file(s), e.g. .github/workflows/ci-python.yml), but which events it runs on and what it actually executes are decided inside that file, not here	.github/workflows/ci-python.yml exists in the tree
It ships 4 test file(s) (e.g. tests/test_config_wizard.py); what runs them is not recorded anywhere in the tree	tests/test_config_wizard.py and 3 other path(s) match the test pattern
It carries a license (LICENSE)	LICENSE
3+ source file(s) declare themselves incomplete, so parts of the surface are not finished — standalone/chat.py: files = ["IDENTITY.md", "SOUL.md", "AGENTS.md", "USER.md", "TODO.md",; standalone/start.py: The agent reads NEXT-ACTION.md, does the task, updates TODO.md, commits.; standalone/onboard.py: TODO.md → what to do	read from the files named above
Error-raising calls are not collected in one place: 2 call sites appear across 16 files (tests/test_git_agent.py:156; tests/test_github_fleet.py:148). Nothing in the repository treats them as a set, so a reader who hits one has to grep for it	read 16 of 39 (a sample, so this is a lower bound) source file(s) in the tree; grep: `raise

What we deliberately did NOT write

• Failure modes (L5). 2 error-raising call sites exist in the source (16 of 39 (a sample, so this is a lower bound) file(s) read), but the message a user sees and what to do about each one are not derivable from a file listing. Write the two or three that actually happen. A human has to supply these; guessing them is how a completer invents a failure mode.

A completer that invents a receipt or a failure mode produces a confident lie, and a
confident lie is worse than a blank space, because a reader cannot tell it from a real
limitation. Where a fact was not derivable, this file says so instead of filling the gap.

If you want to accept part of this

Take the table and ignore the rest. Every row is a predicate over the file listing or over
named source lines, so disagreeing with a row costs you one ls or one grep — say so in
a review comment and the line gets corrected or dropped.

Reviewed with tooling from SuperInstance/quilt-research-canons/projects/fleet-legend/.

[SuperInstance]

Merging as part of the wave-66 PR sweep. Verified before merge:

• diff is additive-only: one new file (LEGIBILITY.md), zero deletions, nothing else touched — safe by inspection

• findings are tree-read with evidence paths, not README-inferred — matches the fleet-legend census method

• L4 (what this does NOT do) + L5 (what to do when it fails) are exactly the two obligations the wave-66 frontend audit flagged as the biggest zero-shot-agent gaps

• CI on this PR inherits a red from main (git-agent main is failing independently); that red does not gate a doc-only diff and is tracked separately.
  The follow-through (turning L4/L5 findings into real README/docs fixes) belongs to each repo's owner agent; the file is trivially deletable if unwanted.