Enum EventTag 

#[repr(u32)]
pub enum EventTag {
    ProjectTrust = 0,
    ResourcesDiscover = 1,
    SessionStart = 2,
    SessionInfoChanged = 3,
    SessionBeforeSwitch = 4,
    SessionBeforeFork = 5,
    SessionBeforeCompact = 6,
    SessionCompact = 7,
    SessionShutdown = 8,
    SessionBeforeTree = 9,
    SessionTree = 10,
    Context = 11,
    BeforeProviderRequest = 12,
    BeforeProviderHeaders = 13,
    AfterProviderResponse = 14,
    BeforeAgentStart = 15,
    AgentStart = 16,
    AgentEnd = 17,
    AgentSettled = 18,
    TurnStart = 19,
    TurnEnd = 20,
    MessageStart = 21,
    MessageUpdate = 22,
    MessageEnd = 23,
    ToolExecutionStart = 24,
    ToolExecutionUpdate = 25,
    ToolExecutionEnd = 26,
    ModelSelect = 27,
    ThinkingLevelSelect = 28,
    ToolCall = 29,
    ToolResult = 30,
    UserBash = 31,
    Input = 32,
    BeforeTuiStart = 33,
    UiPromptStart = 34,
    UiPromptEnd = 35,
    EditorChange = 36,
}

Discriminant for StablePluginEvent, one variant per pi on() category (33 total) plus one rpi-specific category (34 total). #[repr(u32)] pins the discriminant width.

The 33 Pi categories (verified against extensions/types.ts:1203-1244): project_trust, resources_discover, session_start, session_info_changed, session_before_switch, session_before_fork, session_before_compact, session_compact, session_shutdown, session_before_tree, session_tree, context, before_provider_request, before_provider_headers, after_provider_response, before_agent_start, agent_start, agent_end, agent_settled, turn_start, turn_end, message_start, message_update, message_end, tool_execution_start, tool_execution_update, tool_execution_end, model_select, thinking_level_select, tool_call, tool_result, user_bash, input.

BeforeTuiStart is rpi-specific (not a Pi category): dispatched once before the interactive TUI is initialized, so extensions can prepare (connect a server, load a resource) before the UI starts. Appended last so existing discriminants keep their values (ABI-safe for already-compiled plugins).

Variants

ProjectTrust = 0

ResourcesDiscover = 1

SessionStart = 2

SessionInfoChanged = 3

SessionBeforeSwitch = 4

SessionBeforeFork = 5

SessionBeforeCompact = 6

SessionCompact = 7

SessionShutdown = 8

SessionBeforeTree = 9

SessionTree = 10

Context = 11

BeforeProviderRequest = 12

BeforeProviderHeaders = 13

AfterProviderResponse = 14

BeforeAgentStart = 15

The start of a run, carrying the user prompt ({"prompt", "imageCount", "sessionId", "host"}). Fire-and-forget like every other tag: subscribe to observe the turn. To change the system prompt for the run, register a handler with register_before_agent_start — that slot carries an out pointer, which this fire-and-forget signature cannot.

AgentStart = 16

AgentEnd = 17

AgentSettled = 18

TurnStart = 19

TurnEnd = 20

MessageStart = 21

MessageUpdate = 22

MessageEnd = 23

ToolExecutionStart = 24

ToolExecutionUpdate = 25

ToolExecutionEnd = 26

ModelSelect = 27

ThinkingLevelSelect = 28

ToolCall = 29

ToolResult = 30

UserBash = 31

Input = 32

BeforeTuiStart = 33

rpi-specific: dispatched before the interactive TUI initializes (not a Pi on() category). Appended last so existing discriminants are stable.

UiPromptStart = 34

Pi on() category: dispatched when the TUI shows an interactive prompt (selector, dialog, etc.) that blocks agent work.

UiPromptEnd = 35

Pi on() category: dispatched when the TUI prompt is dismissed.

EditorChange = 36

rpi-specific (not a Pi on() category): dispatched whenever the interactive prompt editor’s text changes — typing, pasting, deleting, or a programmatic rewrite. Appended last so existing discriminants are stable. The payload is {"chars":N,"empty":bool}; the draft text itself is deliberately not shipped, because subscribers (a voice extension barging in on playback) only need to know that the user is composing.

Trait Implementations

impl Clone for EventTag

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for EventTag

impl Debug for EventTag

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for EventTag

impl PartialEq for EventTag

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for EventTag