LangBot/docs/architecture/certified-plugins.md

Certified Plugins

Admission boundary

Core verifies a plugin archive before artifact storage, PluginSetting persistence, or a Plugin Runtime apply request. It calls the SDK public langbot_plugin.certification.verify_archive() API, which reads the strict certificate envelope from the ZIP comment and verifies the signed normalized ZIP digest without extracting the payload.

Core retains the normalized digest (normalized_zip_digest()), verification state, declared shared-runtime profile, key ID, selected admission profile, and stable admission code in the durable plugin install_info._certification record. The record belongs to the installation row; no schema migration is needed for this additive JSON metadata.

Trusted issuer configuration

Configure the non-secret Ed25519 public-key ring in data/config.yaml:

plugin:
  certification:
    trusted_public_keys:
      issuer-2026-q3: "<base64 encoded 32-byte Ed25519 public key>"

Key IDs must match the SDK envelope. Values are standard base64 raw public keys, not private/signing keys. An invalid key-ring configuration is rejected rather than weakening verification. Keep active issuer keys during a rotation until archives signed by retired IDs are no longer installed.

The ring may also be supplied out-of-band, which is how hosted deployments provision it:

PLUGIN__CERTIFICATION__TRUSTED_PUBLIC_KEYS_JSON='{"ed25519:issuer":"<base64>"}'

An empty ring is a supported state, not a misconfiguration. OSS defaults to it, so a self-hosted instance that has not provisioned any issuer key still installs packages (see the admission matrix below). Configure the ring to grant the shared-runtime profile; leave it empty to keep every package on the dedicated profile.

Admission matrix

Deployment	SDK verification	Explicit administrator_force	Result
Cloud	valid envelope declaring shared-runtime-v1	any	admitted to the shared profile
Cloud	absent	any	reject before storage with CERTIFIED_PLUGIN_CLOUD_CERTIFICATE_REQUIRED
Cloud	malformed, untrusted, invalid, or non-shared	any	reject before storage with CERTIFIED_PLUGIN_CLOUD_CERTIFICATE_INVALID
OSS	absent legacy envelope	any	admitted to the dedicated profile
OSS	valid envelope declaring shared-runtime-v1	any	selected shared profile
OSS	declaration signed by a key this instance resolves	false	reject with CERTIFIED_PLUGIN_OSS_FORCE_REQUIRED
OSS	declaration signed by a key this instance resolves	true	admitted to the dedicated profile
OSS	declaration this instance cannot resolve (empty ring)	any	admitted to the dedicated profile

The OSS row that matters for availability is the last one. Marketplace packages are signed by the marketplace issuer and declare shared-runtime-v1, while OSS ships an empty key ring by default. Treating that as a rejection made every certified marketplace package uninstallable with CERTIFIED_PLUGIN_OSS_FORCE_REQUIRED before artifact storage. Because the certificate is signed by an issuer the instance does not declare trusted, no shared-runtime privilege may be granted, so admission degrades the install to the existing oss_dev dedicated profile and records CERTIFIED_PLUGIN_OSS_UNTRUSTED_DEDICATED. This is not an escalation: it withholds the shared profile rather than granting it.

A declaration is "resolvable" only when its key_id is present in the configured ring. When the ring is configured and the declaration still fails (malformed, signature_invalid, digest_mismatch, unsupported_schema, ...), admission stays explicit and requires administrator_force.

administrator_force is deliberately strict: it is recognized only when the install request carries boolean true. The local upload endpoint accepts the multipart field administrator_force=true; GitHub and marketplace install payloads carry the same field. The existing resource-manage authorization fence protects those endpoints. A force never creates a Cloud dedicated fallback.

Runtime and logs

The current Plugin Runtime control protocol has one process-wide runtime profile per Core instance. In Cloud that existing profile is shared; Cloud admission therefore prevents an archive that did not select shared-runtime-v1 from reaching its apply API. In OSS the existing oss_dev runtime remains the dedicated compatibility profile. Core records the selected profile for every installation so a future multi-runtime control protocol can consume it without re-verifying an already persisted archive.

The existing public plugin-log boundary already applies the immutable installation binding (including workspace UUID) through RuntimeConnectionHandler.installation_scope() before requesting logs. This is the actual tenant exposure boundary, so valid shared certificates use that binding-scoped transport; Core does not invent a second log stream or expose process-wide log output. Dedicated and invalid/legacy installations use the same existing installation scope.

SDK versioning

Core intentionally continues to declare langbot-plugin==0.5.8 until the SDK beta containing this public certification API is released. Local development and the integration tests may install the SDK source checkout, but this Core change does not publish or pin a prerelease.