Node: Add post user prompt hook

[SteveSandersonMS]

Summary

• add Node SDK typed support for onPostUserPromptSubmitted
• dispatch the runtime postUserPromptSubmitted hook through hooks.invoke
• add a replayed Node E2E snapshot showing transformedPrompt mutation after runtime prompt transformation

[github-actions]

Cross-SDK Consistency Review 🔍

This PR adds the postUserPromptSubmitted hook to the Node.js SDK. A quick scan of the other five SDK implementations shows this hook is not yet present in any of them.

SDKs that already have userPromptSubmitted but are missing postUserPromptSubmitted:

SDK	userPromptSubmitted	postUserPromptSubmitted
Node.js ✅ (this PR)	✅	✅
Python (python/copilot/session.py)	✅	❌
Go (go/types.go, go/session.go)	✅	❌
.NET (dotnet/src/Types.cs, dotnet/src/Session.cs)	✅	❌
Java (java/src/main/java/.../rpc/)	✅	❌
Rust (rust/src/hooks.rs)	✅	❌

Suggested additions per SDK (to match the Node.js contract):

• Input fields: prompt (original) + transformedPrompt (runtime-enriched), plus the base fields (sessionId, timestamp, workingDirectory/cwd).
• Output fields: modifiedTransformedPrompt? and suppressOutput?.

Rough equivalents for each SDK

Python (python/copilot/session.py)

class PostUserPromptSubmittedHookInput(TypedDict):
    sessionId: str
    timestamp: datetime
    workingDirectory: str
    prompt: str
    transformedPrompt: str

class PostUserPromptSubmittedHookOutput(TypedDict, total=False):
    modifiedTransformedPrompt: str
    suppressOutput: bool

PostUserPromptSubmittedHandler = Callable[
    [PostUserPromptSubmittedHookInput, dict[str, str]],
    PostUserPromptSubmittedHookOutput | None | Awaitable[...],
]

Wire into the hook dispatch map at "postUserPromptSubmitted" and add on_post_user_prompt_submitted to SessionHooks.

Go (go/types.go, go/session.go)

type PostUserPromptSubmittedHookInput struct {
    SessionID        string    `json:"sessionId"`
    Timestamp        time.Time `json:"-"`
    WorkingDirectory string    `json:"cwd"`
    Prompt           string    `json:"prompt"`
    TransformedPrompt string   `json:"transformedPrompt"`
}

type PostUserPromptSubmittedHookOutput struct {
    ModifiedTransformedPrompt string `json:"modifiedTransformedPrompt,omitempty"`
    SuppressOutput            bool   `json:"suppressOutput,omitempty"`
}

type PostUserPromptSubmittedHandler func(
    input PostUserPromptSubmittedHookInput,
    invocation HookInvocation,
) (*PostUserPromptSubmittedHookOutput, error)

Add OnPostUserPromptSubmitted PostUserPromptSubmittedHandler to SessionHooks and a case "postUserPromptSubmitted": in session.go.

.NET (dotnet/src/Types.cs, dotnet/src/Session.cs)

public sealed class PostUserPromptSubmittedHookInput
{
    [JsonPropertyName("sessionId")] public string SessionId { get; set; } = string.Empty;
    [JsonPropertyName("timestamp")] public long Timestamp { get; set; }
    [JsonPropertyName("cwd")] public string WorkingDirectory { get; set; } = string.Empty;
    [JsonPropertyName("prompt")] public string Prompt { get; set; } = string.Empty;
    [JsonPropertyName("transformedPrompt")] public string TransformedPrompt { get; set; } = string.Empty;
}

public sealed class PostUserPromptSubmittedHookOutput
{
    [JsonPropertyName("modifiedTransformedPrompt")] public string? ModifiedTransformedPrompt { get; set; }
    [JsonPropertyName("suppressOutput")] public bool? SuppressOutput { get; set; }
}

Add OnPostUserPromptSubmitted property to SessionHooks and handle "postUserPromptSubmitted" in Session.cs.

Java (java/src/main/java/.../rpc/)

`@JsonIgnoreProperties`(ignoreUnknown = true)
public record PostUserPromptSubmittedHookInput(
    `@JsonProperty`("sessionId") String sessionId,
    `@JsonProperty`("timestamp") long timestamp,
    `@JsonProperty`("cwd") String cwd,
    `@JsonProperty`("prompt") String prompt,
    `@JsonProperty`("transformedPrompt") String transformedPrompt) {}

public record PostUserPromptSubmittedHookOutput(
    `@JsonProperty`("modifiedTransformedPrompt") String modifiedTransformedPrompt,
    `@JsonProperty`("suppressOutput") Boolean suppressOutput) {}

Add PostUserPromptSubmittedHandler interface, wire setOnPostUserPromptSubmitted into SessionHooks, and add a case "postUserPromptSubmitted": in CopilotSession.java.

Rust (rust/src/hooks.rs)

pub struct PostUserPromptSubmittedInput {
    pub session_id: String,
    pub timestamp: i64,
    #[serde(rename = "cwd")]
    pub working_directory: PathBuf,
    pub prompt: String,
    pub transformed_prompt: String,
}

pub struct PostUserPromptSubmittedOutput {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub modified_transformed_prompt: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub suppress_output: Option<bool>,
}

Add a PostUserPromptSubmitted variant to HookEvent/HookOutput, a default on_post_user_prompt_submitted method on the Hooks trait, and the matching parse/dispatch arms.

This is a suggestion for follow-up work rather than a blocker for this PR. The Node.js implementation establishes the contract cleanly; the other SDKs can follow the same pattern.

Generated by SDK Consistency Review Agent for issue #1774 · sonnet46 807.4K · ◷