chimera-list-exemptions-not-obligations
A gate that lists what to check fails open — the site nobody remembered to add is the one that breaks. List the exemptions instead, each with a written reason, and the default becomes fail.
Conferred by a reviewer who read the card, not claimed by the file about itself. A card the agent distils during a run that consumed untrusted content is born tainted and is held for review before it is ever retrieved.
When it comes to mind
- writing a build gate
- enforcing a rule across the whole package
- a hand-maintained list of files to check
- a surface lost its guarantee
- adding a new entry point
Avoid and Check are where the value usually is. Do is the section everybody writes.
Trigger
You are enforcing a property that has to hold at every site of a certain kind: every unattended surface goes through the governance profile, every writer passes the gate, every API route regenerates its schema. The rule is one sentence, but the sites are written at different times by different hands, and none of them calls the thing the others call.
It does not apply when the population is closed by construction — a rule about the three entries of a dispatch table is already enumerated by the table. This pattern earns its cost only when a new site can appear in a file that does not exist yet.
Do
- Enumerate the population mechanically. Walk every
*.pyunder the package (PACKAGE.rglob("*.py")), not a hand-written list of the files you happen to know about. - Detect the site structurally. Parse and walk the AST for the call you care about; a
grepcannot tell an assembled registry from the same words inside a docstring, and that docstring will exist, because someone will write a comment about the fix. - Walk nested scopes and key by the enclosing chain —
chimera/cli/main.py:solve._run_solve. The one surface Chimera lost had its registry built inside afactory()closure (chimera/server/manager.py:_gateway_on_message.factory), invisible to a walk that only looked at top-level functions. - Make the default FAIL. Keep one
EXEMPT: dict[str, str]from site key to written reason, and have the assertion list every site found that is not a key in it. - Write the reason as a sentence about that specific site, and separate the kinds of reason. "attended: interactive REPL" (a person can hit Ctrl-C) is a much stronger claim than "assembles an equivalent stack from its own flags" — the second marks a duplicate implementation to consolidate, not a settled answer.
- Add a second test asserting every
EXEMPTkey still names a live site, so the list cannot outlive the code it excuses and rot into a formality.
Avoid
The obligations list:
SURFACES = ["serve", "cron", "mcp", "a2a", "platform"] # fails OPEN
for name in SURFACES:
assert_governed(name)
versus the exemptions list:
EXEMPT = {"chimera/cli/main.py:chat": "attended: interactive REPL"} # fails CLOSED
assert not [s for s in every_site_in_the_package() if s not in EXEMPT]
The first version of Chimera's governance gate was the top one: it parsed a single file and named
five surfaces. chimera/server/manager.py — the Discord bot the desktop app's Messaging toggle
starts, the same bot serve --discord runs — built its registry ungoverned for three weeks after
the sweep that was supposed to have covered it. It was never failing the gate. It was never looked
at.
Also avoid an exemption with no reason. A bare EXEMPT: set[str] is a list of checks to skip that
nobody can review a year later; the one sentence is the whole cost of the entry and the whole value
of it.
Check
Feed the gate a source that violates the rule and assert it is caught, including from inside a nested function — otherwise an AST bug makes the gate pass forever and the guarantee quietly stops existing:
src = "def serve():\n def factory():\n r = default_registry(ws)\n"
assert _bare_registry_calls(ast.parse(src), "m.py") == [("m.py:serve.factory", 3)]
Then the other half: a call already wrapped in the compliant shape must not be flagged, or every conforming site would need an exemption and the list would stop meaning anything.
The binary question: delete one entry from EXEMPT and re-run. Does the suite go red naming exactly
that site? If not, the gate is not reading the list you think it is.
Risk
Inverting the list moves the cost onto whoever adds a legitimate new site: an unrelated PR goes red with an error about governance they were not thinking about. That is the intended trade, but only if the failure message says both ways to comply — route it through the profile, or add the exemption with a reason. A gate that fires on work it was not built to defend gets argued down until it fires on nothing.
The structural detection is also narrower than it feels. It catches the one shape it knows; a surface that assembles tools through a different call, or imports a pre-built registry from elsewhere, is outside the walk and the green build says nothing about it. Pin the coverage of the file that regressed by name in its own test, so a walk that silently stops covering that file fails instead of passing.
Use it
The card is data. Clone the repository and import it by path — anything that arrives over the network is treated as tainted and held for approval, which is the behaviour you want and the reason there is no one-line installer here.
git clone https://github.com/brcampidelli/chimera-agent.gitchimera skills-import chimera-agent/skills/chimera-list-exemptions-not-obligations/SKILL.mdIntegrity
SHA-256 of the file as published. An importer can check that what it received is what this page showed.
243034feb6f9a9a06be65cfb2bf4db159e4fbcc0e7210475dffe540600227ef7