feat(slack): add Send and Wait for Response component

[nenadilic84]

Summary

• Implements the Slack "Send and Wait for Response" component (slack.sendAndWait) that sends a message with configurable buttons to a Slack channel and pauses the workflow until a user clicks a button or an optional timeout expires
• Implements handleInteractivity() in the Slack integration to route button click payloads from Slack to subscribed components via the existing subscription mechanism
• Adds chat.update client method for updating messages after interaction (showing which button was clicked, or indicating timeout)
• Includes full frontend mapper with custom state handling (waiting, received, timed_out)

Architecture

The component follows the established async execution pattern (similar to the Approval component):

1. Execute() sends a Block Kit message with buttons via chat.postMessage, stores the message timestamp as a KV for correlation, optionally schedules a timeout action, and returns nil without emitting — leaving the execution in a waiting state
2. handleInteractivity() (new) parses Slack's form-urlencoded interaction payload, lists subscriptions matching interactivityTypes, and routes the payload via SendMessage()
3. OnIntegrationMessage() receives the interaction and emits it as an event for the node's queue
4. ProcessQueueItem() finds the waiting execution via FindExecutionByKV("message_ts", ...) and completes it by emitting on the received channel
5. HandleAction("timeout") completes the execution on the timeout channel if no response arrives in time

Configuration

Field	Type	Required	Description
Channel	integration-resource	Yes	Slack channel or DM
Message	text	Yes	Message text (supports Slack markdown)
Timeout	number	No	Max seconds to wait
Buttons	list (1-4 items)	Yes	Each with name (label) and value

Output Channels

• Received: Emitted when a user clicks a button; payload includes value and user info
• Timeout: Emitted when no button click within the configured timeout

Files Changed

New files:

• pkg/integrations/slack/send_and_wait.go — Core component implementation
• pkg/integrations/slack/send_and_wait_test.go — Tests for setup, execute, actions, queue processing, and helpers
• pkg/integrations/slack/example_output_send_and_wait.json — Example output
• web_src/src/pages/workflowv2/mappers/slack/send_and_wait.ts — Frontend mapper

Modified files:

• pkg/integrations/slack/slack.go — Register component, implement handleInteractivity(), extend SubscriptionConfiguration
• pkg/integrations/slack/client.go — Add UpdateMessage method
• pkg/integrations/slack/example.go — Add ExampleOutput() for SendAndWait
• web_src/src/pages/workflowv2/mappers/slack/index.ts — Register mapper and state registry

Test plan

• Unit tests pass for Setup validation (missing channel, message, buttons, too many buttons)
• Unit tests pass for Execute (sends Block Kit message, stores KV, schedules timeout)
• Unit tests pass for ProcessQueueItem (routes interactions to waiting executions)
• Unit tests pass for HandleAction timeout (emits on timeout channel)
• Unit tests pass for OnIntegrationMessage (filters non-superplane interactions)
• Unit tests pass for helper functions (extractMessageTS, extractButtonValue, etc.)
• Integration test: send message with buttons, click button, verify workflow continues
• Integration test: send message with timeout, let it expire, verify timeout channel

Closes #2338

[nenadilic84]

Demo video coming shortly — recording the end-to-end flow (integration setup + sending a message with buttons and receiving a user response).

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