risk-boundary-build — Runtime boundaries on msdmd

risk-boundary-build is an application of msdmd. It
turns hidden permission, storage, network, and user-data effects into
module-local declarations that can be reviewed before an agent edits a
sensitive file.

This complements meta-module-build: MODULE_BUILD describes intended
boundaries before new work starts; BOUNDARIES records the actual runtime
boundary of an existing module.

Implementation status: this skill defines the BOUNDARIES block and runner
contract. This repo does not currently ship a BOUNDARIES runner script;
consuming repos should implement the contract below with local risk heuristics.

The block

# === BOUNDARIES ===
# id: chat_route_user_data_boundary
#   summary: reads user-owned chat rows for the authenticated requester
#   auth_boundary: read
#   storage_boundary: read
#   network_boundary: none
#   user_data_boundary: read
#   admin_only: false
#   pii: possible
#   owner: platform-runtime
# === END BOUNDARIES ===

Field schema

Required:

Field	Meaning
id	Stable boundary declaration id.
summary	One-sentence description of the sensitive behavior.
auth_boundary	none, read, write, admin, or hmmm.
storage_boundary	none, read, write, delete, migration, or hmmm.
network_boundary	none, internal, external, or hmmm.
user_data_boundary	none, read, write, delete, or hmmm.
admin_only	true, false, or hmmm.

Optional:

Field	Meaning
pii	none, possible, direct, sensitive, or hmmm.
secrets	none, read, write, or hmmm.
side_effects	Comma-separated side effects (email, webhook, billing, job, cache, etc.).
review_required	Person, role, team, or condition required before edits.
owner	Person, role, or team responsible for the boundary declaration.
requires	Comma-separated BOUNDARIES or MODULE_BUILD ids this declaration depends on.
since	Version or date the declaration was added.

Runner contract

A BOUNDARIES runner MUST:

1. Parse every BOUNDARIES block with the universal msdmd parser.
2. Report required fields containing hmmm as unresolved boundary objects.
3. Report modules with likely sensitive imports or filenames but no
   BOUNDARIES block as visible gaps.
4. Support strict mode where gaps or any required hmmm boundary fail.
5. Exit non-zero for malformed required fields, invalid enum values, or
   strict-mode unresolved boundaries.

Sensitive-file heuristics MAY include auth/session imports, database clients,
network clients, migration filenames, admin routes, payment/billing modules,
secret managers, and user-data models. Heuristics are advisory: they create
review visibility, not proof of risk.

Agent behavior

When this skill is loaded before editing code:

• Read the BOUNDARIES block before changing implementation.
• If a required boundary is hmmm, preserve that uncertainty and call it out.
• Do not relax a boundary value (admin → read, external → internal, etc.)
  unless the code change actually removes the effect.
• If the edit adds a new sensitive effect, update the block in the same diff.

Anti-patterns

• Treating none as a default. Unknown is hmmm, not none.
• Recording intended boundaries in BOUNDARIES before code exists; use MODULE_BUILD first.
• Hiding risk in prose comments instead of structured fields.
• Letting heuristic gap detection replace explicit owner review.

hmmm

• exact sensitive-import heuristic lists per framework
• whether strict mode should fail all hmmm boundaries or only user-data/admin ones
• how to represent read-only analytics on anonymized aggregate data