fix(dashboard): new agents appear at once, not on the 30 s poll (#3109)

[dolho]

Summary

On a fresh install, after the first-run overlay closed, the dashboard Timeline stayed empty for about 30 s, although setup had already seeded four agents. The issue names three gaps, and this fixes all of them:

1. The overlay refetched nothing on close. Dashboard now watches the overlay's v-model:open and calls networkStore.fetchAgents() when it goes from true to false, as onCreateModalClose does for the create modal. This covers finish, skip and confirm-close. Setup's seeding doesn't go through the crud create path, so this refetch is what fixes the reported case.
2. stores/network.js had no agent_created handler. It now refetches the REST list, which is access-controlled and tag-filtered and carries the full row, instead of inserting the broadcast's partial row (feat: agent-reported structured reports via MCP + dashboard display #918 thin trigger). A burst of creates is merged into one refetch (300 ms).
3. agent_created / agent_deleted had no type key, and the dashboard dispatches on type. Both now send it, like agent_started / agent_stopped already do. This also revives the dead agent_deleted branch, which now reads the name from data.data, where it actually is.

The ent#467 /ws scoping reads event first, so it's unaffected; its tests pass.

Changes

• src/backend/services/agent_service/crud.py, src/backend/routers/agents.py: add "type" to the agent_created and agent_deleted broadcasts
• src/frontend/src/stores/network.js: the agent_created handler (coalesced refetch) and the revived agent_deleted branch
• src/frontend/src/views/Dashboard.vue: refetch when the first-run overlay closes
• Tests:
  • tests/unit/test_3109_agent_ws_type.py
  • src/frontend/tests/unit/networkAgentCreatedWs.spec.js
  • src/frontend/tests/unit/dashboardFirstRunRefetch.mount.spec.js

Test Plan

• Backend:
  • the real _broadcast_agent_created payload carries type;
  • an AST guard requires every agent lifecycle broadcast to carry a matching type, so a new event added with event only fails.
• Store: the store's own WebSocket is fed the backend's envelope:
  • 4 creates cause 1 refetch;
  • the broadcast payload is never inserted;
  • agent_deleted removes the agent.
• Dashboard (mounted): closing the overlay refetches; opening it doesn't.
• Mutation: reverting each source file turns its tests red. crud.py: 2; agents.py: 1; network.js: 3; Dashboard.vue: 1.
• Full frontend suite: 4,499 passed. check-design-tokens and npm run build: OK. Related backend suites (ent#467 scoping, ent#107 seed, capacity, backlog): 148 passed.

Fixes #3109

🤖 Generated with Claude Code

[dolho]

/review report: fix/3109-dashboard-agent-created → dev

Files changed: 8 (+297/-1, including a learnings fragment). Scope: CLEAN. Plan completion: 3/3 suggested-scope items done:

• refetch on overlay close;
• an agent_created handler;
• type on the broadcasts, reviving agent_deleted.

Execution coverage

changed symbol	executed by	live consumer	verdict
_broadcast_agent_created type	test_3109_agent_ws_type.py (real call)	stores/network.js dispatcher	✅
agents.py agent_deleted type (both sites)	the AST guard in the same file	the same dispatcher	🛡 guard (its live consumer is the dispatcher)
network.js agent_created → coalesced fetchAgents	networkAgentCreatedWs.spec.js (store's own socket)	Dashboard / Timeline	✅
network.js revived agent_deleted	same	same	✅
Dashboard.vue overlay-close refetch	dashboardFirstRunRefetch.mount.spec.js	FirstRunOverlay v-model	✅

Fix mutations: reverting each file turns its tests red. crud.py: 2; agents.py: 1; network.js: 3; Dashboard.vue: 1.

Live check (local dev stack, 2026-10-01, dev + this PR)

With the dashboard open, an agent was created through POST /api/agents:

• it appeared on the dashboard 0.53 s after creation (before this PR: the 30 s poll);
• after DELETE it disappeared after 0.52 s.

Both test agents were removed.

Critical findings

None.

Informational

• [I1] utils/websocket.js still pushes the agent_created payload into agentsStore as a partial row (pre-existing). With ent#467's per-agent /ws scoping it only reaches viewers with access, and fetchAgents write-through replaces it on the next read. Not introduced here; noted for consistency with the refetch rule this PR follows.
• [I2] The coalescing timer isn't cleared on disconnectWebSocket (confidence 5/10). Worst case is one extra harmless fetchAgents after a disconnect.

Clean categories

• ent#467 scoping: reads event first; test_ent467_ws_agent_scope.py passes.
• Disclosure: the broadcast payload is unchanged apart from type.
• Docs: bug-fix tier (commit message). A learnings fragment was added for the recurring "producer shape ≠ dispatcher key" class: docs/memory/learnings/2026-10-01-ws-event-vs-type-key.md.

Summary: Critical 0 · Informational 2 · Scope clean.

[vybe]

merge-train: batch validated on train #3172