fix(triggers): support multiple subscriptions per (connection, type) and cascade on connection delete

[viktormarinho]

Summary

The trigger registration system collapsed multiple subscriptions on the same (connection, event_type) into a single slot, overwriting credentials and wiping callbacks when one of them was disabled. Connection deletion also left orphan state on MCPs because mesh never told the MCP a subscription should disappear.

This PR carries three fixes:

• bindings + runtime: TRIGGER_CONFIGURE gains an optional subscriptionId. The runtime's TriggerStateManager keys credentials by (connectionId, subscriptionId) instead of connectionId alone, and the TriggerStorage interface gains a list(connectionId) method so notify can fanout to every subscription on a connection. The legacy __default slot keeps single-sub MCPs working unchanged.
• mesh storage: trigger_callback_tokens gets a subscription_id column (= automation_triggers.id). The unique index moves from (connection_id, organization_id) to subscription_id, with a non-unique lookup index left on the old pair. persistTokenHash/deleteBySubscription/listByConnection all key on the new column. Migration 077 backfills existing rows and ships the index swap.
• mesh handlers: trigger-add pre-allocates the trigger id before calling the MCP, then reuses it on the DB insert, so configure and persistence agree on the same subscriptionId. automation/delete now passes tokenStorage so per-subscription tokens are cleaned up. connection/delete runs TRIGGER_CONFIGURE(enabled=false) on every event trigger bound to the connection before the row is removed — this stops the orphan accumulation we observed in the gmail MCP, where deleted-and-recreated connections left dead triggers:<connId> records in KV.

Why

Studio assigns one connectionId per OAuth credential and reuses it across automations. Each automation registers its own trigger with a fresh callback token. The previous runtime stored only the latest token, so:

• Adding two automations on the same Gmail connection meant the second's enable overwrote the first's token.
• Deleting any automation on a connection wiped every sibling's credentials because disable removed the entire connection record once activeTriggerTypes reached zero.
• Deleting a connection in studio silently dropped tokens locally without telling the MCP, leaving permanent triggers:<connId> orphans that fired "nobody subscribed" on every webhook delivery for that email afterwards.

After this PR the MCP can hold N independent subscriptions per connection, mesh tracks each separately end-to-end, and connection deletion is a clean cascade.

Schema migration

077-trigger-callback-tokens-per-subscription.ts adds subscription_id, backfills existing rows with subscription_id = id (self-reference; rows stay validatable until the next TRIGGER_CONFIGURE writes a fresh id-keyed row), drops the old unique index on (connection_id, organization_id), and creates idx_trigger_callback_tokens_subscription. A non-unique idx_trigger_callback_tokens_connection_org_lookup is kept for the connection-cascade query path.

Backward compatibility

subscriptionId is optional in the bindings schema. MCPs running an older runtime ignore the field. Studio versions that haven't been updated yet keep working — they fall through to the __default slot in the new runtime, which preserves the single-sub-per-connection semantics they expect.

Test plan

• bun test in packages/runtime — 15/15 pass, including new tests for sibling-disable, multi-sub fanout, and legacy-default fallback
• bun test in apps/mesh for src/storage src/automations src/tools/automations src/tools/connection — 211 pass, 1 skip, 0 fail
• Migration applies cleanly in test schema (77/77 migrations green)
• bun run check clean in packages/runtime and packages/bindings
• bun run check in apps/mesh produces only one pre-existing error in delete-organization-section.tsx (unrelated to this PR)
• End-to-end smoke: add two automations on the same connection with different filter params, fire a matching event, verify both callback URLs receive it

Follow-up (not in this PR)

The gmail MCP at decocms/mcps will adopt the new TriggerStorage interface and update its webhook handler to fanout via list(connectionId). Filed separately so this PR can land independently.

🤖 Generated with Claude Code

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Summary by cubic

Enable multiple event trigger subscriptions per connection and cleanly disable them on connection delete. Fixes token overwrites between automations and stops orphaned MCP trigger state.

• New Features

  • TRIGGER_CONFIGURE accepts optional subscriptionId; runtime keys by (connectionId, subscriptionId) and fans out on notify.
  • Mesh stores callback tokens per subscription (trigger_callback_tokens.subscription_id with a unique index); token APIs updated to use subscription ids.
  • trigger-add pre-allocates the trigger id and reuses it for MCP configure; automation/delete and connection/delete disable MCP subscriptions and remove tokens per subscription.
  • Backward compatible: if subscriptionId is missing, the legacy __default slot is used.

• Migration

  • Adds migration 077 to add subscription_id, backfill existing rows, and swap indexes; run app migrations.
  • No breaking changes; passing subscriptionId is recommended to enable multiple subscriptions.

^{Written for commit 2a4e59c. Summary will update on new commits.}

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Suggested: Patch (2.311.4) — based on fix: prefix

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Current version: 2.311.3

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