Rejection Codes Reference

Command rejection codes are returned by domain deciders when a command violates business rules. They appear in command.Rejection.Code and are surfaced to clients through gRPC error details.

Naming Convention

All codes use SCREAMING_SNAKE_CASE with a domain prefix matching the aggregate or concern that owns the rule:

CAMPAIGN_ – campaign aggregate
PARTICIPANT_ – participant aggregate
CHARACTER_ – character aggregate
SESSION_ – session aggregate
SCENE_ – scene aggregate
INVITE_ – invite aggregate
SESSION_READINESS_ – readiness evaluation (not a decider rejection)

System-specific codes use the system’s own vocabulary (e.g., GM_FEAR_, DAMAGE_, ADVERSARY_ for Daggerheart).

Shared Codes

Defined in domain/command/:

Code	When
`PAYLOAD_DECODE_FAILED`	Command payload JSON unmarshalling failed
`COMMAND_TYPE_UNSUPPORTED`	No handler registered for the command type

Campaign

Defined in domain/campaign/:

Code	When
`CAMPAIGN_ALREADY_EXISTS`	Duplicate campaign create
`CAMPAIGN_NOT_CREATED`	Operation on a campaign that hasn’t been created
`CAMPAIGN_NAME_EMPTY`	Name is blank after trimming
`CAMPAIGN_INVALID_GAME_SYSTEM`	Unrecognized game system identifier
`CAMPAIGN_INVALID_GM_MODE`	Unrecognized GM mode
`CAMPAIGN_UPDATE_EMPTY`	Update with no changed fields
`CAMPAIGN_INVALID_STATUS`	Unrecognized status value
`CAMPAIGN_INVALID_STATUS_TRANSITION`	Illegal lifecycle transition
`CAMPAIGN_UPDATE_FIELD_INVALID`	Unknown field key in update payload
`CAMPAIGN_LOCALE_INVALID`	Unrecognized locale string
`CAMPAIGN_COVER_ASSET_INVALID`	Invalid cover asset identifier
`CAMPAIGN_COVER_SET_INVALID`	Invalid cover set identifier
`CAMPAIGN_AI_AGENT_ID_REQUIRED`	AI bind without agent ID
`CAMPAIGN_PARTICIPANTS_REQUIRED`	Operation requires participants
`CAMPAIGN_PARTICIPANT_DUPLICATE`	Duplicate participant in batch

Participant

Defined in domain/participant/:

Code	When
`PARTICIPANT_ALREADY_JOINED`	Duplicate join
`PARTICIPANT_NOT_JOINED`	Operation on absent participant
`PARTICIPANT_ID_REQUIRED`	Missing participant ID
`PARTICIPANT_NAME_EMPTY`	Name is blank
`PARTICIPANT_INVALID_ROLE`	Unrecognized role
`PARTICIPANT_INVALID_CONTROLLER`	Unrecognized controller type
`PARTICIPANT_INVALID_CAMPAIGN_ACCESS`	Unrecognized access level
`PARTICIPANT_INVALID_AVATAR_SET`	Invalid avatar set ID
`PARTICIPANT_INVALID_AVATAR_ASSET`	Invalid avatar asset ID
`PARTICIPANT_UPDATE_EMPTY`	No changed fields
`PARTICIPANT_UPDATE_FIELD_INVALID`	Unknown field key
`PARTICIPANT_ALREADY_CLAIMED`	Seat already owned
`PARTICIPANT_USER_ID_REQUIRED`	Missing user ID
`PARTICIPANT_USER_ID_MISMATCH`	Claim by wrong user
`PARTICIPANT_AI_ROLE_REQUIRED`	AI participant missing role
`PARTICIPANT_AI_ACCESS_REQUIRED`	AI participant missing access
`PARTICIPANT_AI_USER_ID_FORBIDDEN`	AI participant with user ID
`PARTICIPANT_AI_IDENTITY_LOCKED`	AI participant identity change

Character

Defined in domain/character/:

Code	When
`CHARACTER_ALREADY_EXISTS`	Duplicate character create
`CHARACTER_ID_REQUIRED`	Missing character ID
`CHARACTER_NAME_EMPTY`	Name is blank
`CHARACTER_KIND_INVALID`	Unrecognized kind
`CHARACTER_INVALID_AVATAR_SET`	Invalid avatar set
`CHARACTER_INVALID_AVATAR_ASSET`	Invalid avatar asset
`CHARACTER_NOT_CREATED`	Operation on absent character
`CHARACTER_UPDATE_EMPTY`	No changed fields
`CHARACTER_UPDATE_FIELD_INVALID`	Unknown field key
`CHARACTER_ALIASES_INVALID`	Malformed alias list
`CHARACTER_OWNER_PARTICIPANT_ID_REQUIRED`	Missing owner

Session

Defined in domain/session/:

Code	When
`SESSION_ID_REQUIRED`	Missing session ID
`SESSION_ALREADY_STARTED`	Duplicate session start
`SESSION_NOT_STARTED`	Operation on inactive session
`SESSION_GATE_ID_REQUIRED`	Missing gate ID
`SESSION_GATE_TYPE_REQUIRED`	Missing gate type
`SESSION_GATE_PARTICIPANT_REQUIRED`	Missing gate participant
`SESSION_GATE_ALREADY_OPEN`	Duplicate gate open
`SESSION_GATE_METADATA_INVALID`	Malformed gate metadata
`SESSION_GATE_NOT_OPEN`	Operation on closed gate
`SESSION_GATE_MISMATCH`	Response to wrong gate
`SESSION_GATE_RESPONSE_INVALID`	Malformed gate response
`SESSION_SPOTLIGHT_TYPE_REQUIRED`	Missing spotlight type

Scene

Defined in domain/scene/:

Code	When
`SCENE_ID_REQUIRED`	Missing scene ID
`SCENE_NAME_REQUIRED`	Name is blank
`SCENE_CHARACTERS_REQUIRED`	Scene created without characters
`SCENE_NOT_FOUND`	Operation on absent scene
`SCENE_NOT_ACTIVE`	Operation on ended scene
`SCENE_GATE_ID_REQUIRED`	Missing scene gate ID
`SCENE_GATE_TYPE_REQUIRED`	Missing scene gate type
`SCENE_GATE_ALREADY_OPEN`	Duplicate scene gate open
`SCENE_GATE_NOT_OPEN`	Response on closed scene gate
`SCENE_CHARACTER_ID_REQUIRED`	Missing character ID in scene op
`SCENE_CHARACTER_ALREADY_IN_SCENE`	Duplicate character add
`SCENE_CHARACTER_NOT_IN_SCENE`	Remove absent character
`SCENE_SPOTLIGHT_TYPE_REQUIRED`	Missing scene spotlight type
`SCENE_SPOTLIGHT_NOT_SET`	Clear when no spotlight active
`SCENE_SOURCE_SCENE_ID_REQUIRED`	Missing source in move
`SCENE_TARGET_SCENE_ID_REQUIRED`	Missing target in move
`SCENE_NEW_SCENE_ID_REQUIRED`	Missing new scene in split

Invite

Defined in domain/invite/:

Code	When
`INVITE_ALREADY_EXISTS`	Duplicate invite create
`INVITE_ID_REQUIRED`	Missing invite ID
`INVITE_PARTICIPANT_ID_REQUIRED`	Missing participant ID
`INVITE_NOT_CREATED`	Operation on absent invite
`INVITE_STATUS_INVALID`	Illegal status transition
`INVITE_USER_ID_REQUIRED`	Missing user ID
`INVITE_JTI_REQUIRED`	Missing JWT identifier

Action

Defined in domain/action/:

Code	When
`REQUEST_ID_REQUIRED`	Missing action request ID
`ROLL_SEQ_REQUIRED`	Missing roll sequence
`OUTCOME_ALREADY_APPLIED`	Duplicate outcome application
`OUTCOME_EFFECT_SYSTEM_OWNED_FORBIDDEN`	Effect type reserved for system
`OUTCOME_EFFECT_TYPE_FORBIDDEN`	Unrecognized effect type

Engine

Defined in domain/engine/:

Code	When
`CAMPAIGN_ACTIVE_SESSION_LOCKED`	Write blocked by active session lock
`SESSION_GATE_OPEN`	Write blocked by open session gate
`SCENE_GATE_OPEN`	Write blocked by open scene gate

Session Readiness

Defined in domain/readiness/. These are evaluation codes, not decider rejections – they describe blockers for session start:

Code	When
`SESSION_READINESS_CAMPAIGN_STATUS_DISALLOWS_START`	Campaign status prevents starting
`SESSION_READINESS_ACTIVE_SESSION_EXISTS`	Another session is already active
`SESSION_READINESS_AI_AGENT_REQUIRED`	AI GM mode but no agent bound
`SESSION_READINESS_AI_GM_PARTICIPANT_REQUIRED`	AI GM mode but no AI participant
`SESSION_READINESS_GM_REQUIRED`	No GM participant
`SESSION_READINESS_PLAYER_REQUIRED`	No player participants
`SESSION_READINESS_CHARACTER_SYSTEM_REQUIRED`	Character missing system data

Daggerheart System

Defined in domain/systems/daggerheart/:

Code	When
`GM_FEAR_AFTER_REQUIRED`	Fear update missing target value
`GM_FEAR_AFTER_OUT_OF_RANGE`	Fear value outside bounds
`GM_FEAR_UNCHANGED`	Fear update with same value
`CHARACTER_STATE_PATCH_NO_MUTATION`	Patch with no actual changes
`CONDITION_CHANGE_NO_MUTATION`	Condition update with no changes
`CONDITION_CHANGE_REMOVE_MISSING`	Remove condition not present
`COUNTDOWN_UPDATE_NO_MUTATION`	Countdown update with no changes
`COUNTDOWN_BEFORE_MISMATCH`	Optimistic lock failure on countdown
`DAMAGE_BEFORE_MISMATCH`	Optimistic lock failure on damage
`DAMAGE_ARMOR_SPEND_LIMIT`	Armor spend exceeds available
`ADVERSARY_DAMAGE_BEFORE_MISMATCH`	Optimistic lock on adversary damage
`ADVERSARY_CONDITION_NO_MUTATION`	Adversary condition no changes
`ADVERSARY_CONDITION_REMOVE_MISSING`	Remove absent adversary condition
`ADVERSARY_CREATE_NO_MUTATION`	Adversary create with no data
`GOLD_INVALID`	Invalid gold value
`DOMAIN_CARD_ACQUIRE_INVALID`	Invalid domain card acquisition
`EQUIPMENT_SWAP_INVALID`	Invalid equipment swap
`CONSUMABLE_INVALID`	Invalid consumable operation
`DOWNTIME_MOVE_LIMIT_HIT`	Downtime move limit exceeded