Enum HookResult 

pub enum HookResult {
    Continue,
    Block {
        reason: String,
    },
    Inject {
        content: String,
    },
    Confirm {
        message: String,
        sources: Vec<String>,
        generations: Vec<u64>,
        tool: Option<String>,
        modified_input: Option<Value>,
        modified_by: Vec<String>,
    },
    Modify {
        input: Value,
    },
    Replace {
        output: String,
    },
    ContextPhase {
        phase: String,
    },
}

What an extension handler returns after processing a hook event.

The runtime resolves multiple handlers by precedence:

• For before_tool_call only Block stops the handler chain. Modify rewrites the input that later handlers see; Confirm is merged and resolved after the whole chain (a Modify after it is ignored).
• Inject results are accumulated for before_message.
• Continue is the no-op default — processing continues normally.

Variants

Continue

Allow execution to proceed unchanged.

Block

Prevent the hooked operation. The reason is surfaced to the user.

Fields

reason: String

Inject

Inject context — the extension provides text for the current request. Placement depends on the hook (#297): on_session_start content is appended to the system prompt (session-stable, cache-safe); before_message content is attached to the newest user message on the outgoing request as an ephemeral trailing block positioned AFTER the conversational cache marker (per-turn, uncached tail, cache-neutral).

Fields

content: String

Confirm

Ask the runtime to get explicit user confirmation before proceeding. Only valid on before_tool_call hooks.

sources / tool are host-stamped by HookBus::emit (the extension id(s) that asked, and the tool name). They are never read from or written to the extension wire format, so an extension cannot claim to be another extension. The “Allow all” latch is keyed by sources.

Fields

message: String

sources: Vec<String>

generations: Vec<u64>

Host-set load generation of each source (parallel to sources; missing entries mean 0). Part of the latch key, so a plugin reinstalled under the same id starts unlatched.

tool: Option<String>

modified_input: Option<Value>

Host-set: the input as rewritten by Modify results earlier in the chain. Approval runs THIS input (never extension-settable).

modified_by: Vec<String>

Host-set: ids of the extensions whose Modify produced modified_input (chain order, de-duplicated). Shown in the prompt so the user knows the input was rewritten, and by whom.

Modify

Replace the tool input before execution (structured JSON args). Only valid on before_tool_call hooks. The output-side counterpart is HookResult::Replace. Does not stop the chain: later handlers see (and may block or confirm) the modified input.

Fields

input: Value

Replace

Replace the tool output after execution (flat string), before it enters history. Only valid on after_tool_call hooks. The input-side counterpart is HookResult::Modify — distinct name because the payload is an unstructured String, not structured Value. Enables native output transforms (compression, redaction, summarization) by extensions. The first transform stops the handler chain.

Fields

output: String

ContextPhase

Advisory work-phase report for the host’s automatic context management. Only valid on on_message_complete, and only honoured when the extension additionally holds session.lifecycle. Semantics are identical to the model calling context_checkpoint with this phase and no note: the host may roll the context window over at the next task boundary. It is a lower-authority report — never capacity, permission, or history authority — and does not stop the handler chain (other observers still run; the first valid report wins). phase is parsed host-side with WorkPhase::parse; unknown strings are ignored with a warning.

Fields

phase: String

Implementations

impl HookResult

pub fn confirm(message: impl Into<String>) -> Self

An unattributed Confirm (as an extension returns it, before HookBus::emit stamps the source).

Trait Implementations

impl Clone for HookResult

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HookResult

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

Formats the value using the given formatter.

impl Default for HookResult

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for HookResult

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for HookResult

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for HookResult

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for HookResult