fix(webhooks): unify session-options factory across desktop/telegram/slack

[OmGuptaIND]

Summary

Investigation triggered by a Telegram bug where the bot returned https://anton.computer/a/<slug> instead of the deployment's ANTON_HOST (e.g. itsomg.antoncomputer.in). Tracing the divergence revealed that the webhook session-options builder had drifted from AgentServer.buildSessionOptions(...) — and that the underlying createSession opts type silently dropped several fields on every Pi SDK session, desktop included.

This PR closes the drift class, ships a CI guard so it can't recur, and fixes the immediate Telegram URL bug along the way.

What was broken on Telegram/Slack (now fixed)

Field	Before	After
domain (publish URL)	relative /a/<slug>	canonical https://<host>/a/<slug>
resolveProviderToken	web_search/web_research returned "not configured"	wired
onActivateWorkflow	tool hidden	available
onSharedState, workflowId/Key	dropped	wired
onDeliverResult	dropped	wired
agentInstructions/agentMemory	dropped on routine runs	wired
thinkingLevel	binding override ignored	applied
liveConnectors	"Active Anton Connectors" prompt block missing	injected
/model after server restart	silently ignored	survives cold start (post-resume reconciliation)

What was also broken on desktop Pi SDK sessions (silent latent bug)

createSession's opts type omitted onActivateWorkflow, onSharedState, workflowId/Key, and thinkingLevel. buildSessionOptions returned them, but TypeScript's excess-property check is silent on object variables, so they were silently dropped. The harness path (Codex/Claude Code) worked because it reads from harnessSessionContexts directly — only Pi SDK was affected. This PR fixes the wiring as a side-effect of unifying the type.

Architectural changes (the structural fix)

1. getPublicHost() helper in @anton/agent-config — 9 process.env.ANTON_HOST reads → 1 greppable consumer.
2. Unified SessionOptions interface in @anton/agent-core — createSession and resumeSession now accept the exact same shape; previously-dropped fields wired into ToolCallbacks / Session ctor.
3. AgentServer.buildSessionOptions declares explicit : SessionOptions return type. Webhook closure delegates straight to it instead of carrying its own (drifty) shape.
4. AgentServer.buildHarnessSessionContext extracted — harness sessions derive shared wiring (domain, project handlers, resolveProviderToken) from the same factory.
5. buildCurrentContextLayer in prompt-layers.ts is now the single source of truth for the "Current Context" block. Pi SDK Session.getSystemPrompt() no longer inlines a duplicate. Adding a field there propagates to desktop, Telegram, Slack, and every harness CLI automatically.
6. check-session-options drift guard — compile-time exhaustiveness via satisfies readonly (keyof SessionOptions)[] + runtime source scan. Adding a SessionOptions field without wiring it through every consumer is now a CI failure.

Side-fixes spotted along the way

• Webhook sessions no longer wire onSubAgentEvent (the desktop AI-channel handler has no place on Telegram/Slack and risked leaking events into a desktop client sharing the same sessionId).
• /model choice survives server restart (post-resume reconciliation: if resolved binding override differs from the persisted provider/model, session.switchModel(...) is called).
• Scheduled-agent harness sessions no longer get recursive activate_workflow (matches the docstring's intent — harness wasn't enforcing it).
• Scheduled-agent harness sessions correctly receive onDeliverResult (was previously dropped).

File map

File	Change
packages/agent-config/src/config.ts	getPublicHost()
packages/agent-core/src/index.ts	export SessionOptions
packages/agent-core/src/prompt-layers.ts	unified buildCurrentContextLayer
packages/agent-core/src/session.ts	SessionOptions type, wired fields
packages/agent-server/package.json	check:session-options script
packages/agent-server/src/server.ts	unified factory, harness-context builder, webhook overrides
packages/agent-server/src/webhooks/agent-runner.ts	WebhookSessionOptions = SessionOptions, post-resume reconciliation
(new) packages/agent-server/src/__fixtures__/check-session-options.ts	drift guard

8 files, +706 / −196.

Test plan

• pnpm --filter @anton/agent-core build clean
• pnpm --filter @anton/agent-server build clean
• pnpm --filter @anton/agent-core check:harness — 77/77 cross-surface checks pass
• pnpm --filter @anton/agent-server check:session-options — 27/27 drift-guard fields verified
• Drift guard manually validated: commenting out onActivateWorkflow: opts?.onActivateWorkflow in createSession causes the script to exit non-zero with the exact field name flagged.
• Smoke-test on a deployment with ANTON_HOST=itsomg.antoncomputer.in: the Telegram bot's publish URL should now point at https://itsomg.antoncomputer.in/a/<slug>, and the model recalling a previously-published artifact from ~/.anton/published/ should reference the same host (not anton.computer).
• Smoke-test /model openrouter/... on Telegram, restart the server, send another message — should still use the override.
• Smoke-test web_search and web_research on Telegram (previously returned "not configured").

🤖 Generated with Claude Code