fix(tasks): stop stamping hedgehog reaction on interim slack relays

[richardsolomou]

Problem

When a Slack-launched task runs, the bot manages a reaction on the user's mention message as a status indicator:

Reaction	Meaning
:seedling:	task received / queued
:eyes:	agent working
:hedgehog:	task completed (or PR opened)
:x:	task failed

post_slack_update is the intended single source of truth for terminal reactions — it only stamps :hedgehog: when the run reaches COMPLETED, CANCELLED, or a PR is opened.

However, every interim agent message posted back into the Slack thread via the relay_message endpoint was also flipping the reaction to :hedgehog:. The endpoint by design only fires for non-terminal runs (it short-circuits on task_run.is_terminal), so users were seeing the "done" hedgehog appear repeatedly while the agent was still working.

Root cause: RelaySlackMessageInput.reaction_emoji defaulted to "hedgehog", and the relay_message endpoint never passed an explicit value, so the default fired on every interim relay.

Changes

• RelaySlackMessageInput.reaction_emoji and execute_posthog_code_agent_relay_workflow's reaction_emoji arg now default to None.
• relay_slack_message only calls handler.update_reaction(...) when the caller explicitly passes a reaction.
• forward_pending_message (the delivery-failure case that legitimately needs to mark :x:) is unchanged — it already passed reaction_emoji=\"x\" explicitly.
• Net effect: interim agent relays no longer touch the reaction. post_slack_update remains the sole authority on lifecycle reactions.

How did you test this code?

• Updated the existing test_relay_posts_message_and_marks_sent test to assert that an interim relay does not call update_reaction.
• Added test_relay_with_explicit_reaction_updates_reaction to confirm an explicit reaction_emoji=\"x\" (the forward_pending_message path) still flows through.
• I'm an agent — no manual testing in a live Slack workspace was performed.

Publish to changelog?

no

Docs update

No docs changes needed.

🤖 Agent context

Authored by Claude Code (Opus 4.7) via the PostHog Code sandbox. The user reported that the hedgehog emoji was appearing on their Slack mention before the task was actually done. Traced the reaction lifecycle through products/slack_app/backend/slack_thread.py:update_reaction, products/tasks/backend/temporal/process_task/activities/post_slack_update.py (intended terminal-state authority), and products/tasks/backend/temporal/slack_relay/activities.py (the bug site).

Considered two fixes:

1. Change the relay default to \"eyes\" so interim messages reaffirm the working indicator.
2. Make reaction_emoji optional (None) and only update the reaction when explicitly set.

Picked (2): the existing forward_pending_message caller already passes \"x\" explicitly, so the parameter is preserved for legitimate state-bearing relays; absence of an arg now means "don't touch it" rather than the previous footgun of "mark as done". This also avoids redundant Slack API calls (the update_reaction flow does a reactions_remove per stale emoji plus a reactions_add) on every interim message.

[greptile-apps]

Comments Outside Diff (1)

1. products/tasks/backend/temporal/slack_relay/tests/test_activities.py, line 68-103 (link)

   These two tests cover mutually complementary cases for the reaction_emoji field (absent → no update_reaction call; explicit value → call fires) and are a good fit for @parameterized.expand. The parameterized import is already present in the file.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: products/tasks/backend/temporal/slack_relay/tests/test_activities.py
   Line: 68-103
   
   Comment:
   These two tests cover mutually complementary cases for the `reaction_emoji` field (absent → no `update_reaction` call; explicit value → call fires) and are a good fit for `@parameterized.expand`. The `parameterized` import is already present in the file.
   
   
   
   How can I resolve this? If you propose a fix, please make it concise.

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
products/tasks/backend/temporal/slack_relay/tests/test_activities.py:68-103
These two tests cover mutually complementary cases for the `reaction_emoji` field (absent → no `update_reaction` call; explicit value → call fires) and are a good fit for `@parameterized.expand`. The `parameterized` import is already present in the file.

```suggestion
    @parameterized.expand(
        [
            ("no_reaction_emoji", "relay-1", "Which license should I use?", None, False, None),
            ("explicit_reaction_emoji", "relay-2", "Could not deliver follow-up", "x", True, "x"),
        ]
    )
    @patch("products.slack_app.backend.slack_thread.SlackThreadHandler.update_reaction")
    @patch("products.slack_app.backend.slack_thread.SlackThreadHandler.post_thread_message")
    @patch("products.slack_app.backend.slack_thread.SlackThreadHandler.delete_progress")
    def test_relay_reaction_behaviour(
        self, _name, relay_id, text, reaction_emoji, expects_update, expected_emoji, mock_delete_progress, mock_post, mock_update
    ):
        relay_slack_message(
            RelaySlackMessageInput(
                run_id=str(self.task_run.id),
                relay_id=relay_id,
                text=text,
                user_message_ts="1234.5",
                reaction_emoji=reaction_emoji,
            )
        )

        mock_delete_progress.assert_called_once()
        mock_post.assert_called_once()
        if expects_update:
            mock_update.assert_called_once_with(expected_emoji)
        else:
            mock_update.assert_not_called()
```

_{Reviews (1): Last reviewed commit: "fix(tasks): stop stamping hedgehog react..." | Re-trigger Greptile}

[github-actions]

ClickHouse migration SQL per cloud environment

No ClickHouse migrations changed in this PR.

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-05-28 16:34 UTC	Run
prod-us	✅ Deployed	2026-05-28 17:00 UTC	Run
prod-eu	✅ Deployed	2026-05-28 17:02 UTC	Run