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Eric Allam c69e939c34 feat: Sessions - bidirectional durable agent streams (#3417)
> ⚠️ **Not released yet.** This PR is the server-side foundation only.
The SDK changes that customers will actually use (`chat.agent`
migration, `chat.createStartSessionAction`, `useTriggerChatTransport`
updates) live on a separate branch and ship together in an upcoming
`@trigger.dev/sdk` prerelease. Until that prerelease is published, this
surface is reachable only via direct HTTP.

## What this gives Trigger.dev users

A new first-class primitive, **Session**, for durable, task-bound,
bidirectional I/O that outlives any single run. Sessions are the run
manager for `chat.agent` going forward, and they unblock anything else
that needs "one identifier, many runs over time" with a stable channel
pair the client can write to and subscribe to.

### Use cases unblocked

- **Chat agents that persist across many runs.** One session per chat
(keyed on your own `chatId` via `externalId`), turns 1..N attach to the
same Session, the UI subscribes once and keeps receiving output as new
runs take over.
- **Approval loops and long-running tasks with user feedback.** The task
waits on `.in`, the client writes to `.in`, the server enforces
no-writes-after-close.
- **Workflow progress streams that live past the run.** Subscribe to
`.out` after the task finishes to replay history.
- **Resume-next-day flows.** A session is a durable row, not a transient
stream. Send a message a day later and the server triggers a fresh run
on the same session.

### How it works (Session-as-run-manager)

A Session row is task-bound (`taskIdentifier` + `triggerConfig` are
required) and owns its current run via `currentRunId` +
`currentRunVersion` for optimistic claim. Three trigger paths:

1. **Session create** — `POST /api/v1/sessions` creates the row and
triggers the first run synchronously.
2. **Append-time probe** — `POST
/realtime/v1/sessions/:session/in/append` checks if the current run is
alive; if it has terminated (idle exit, crash, etc.), the server
triggers a new run before processing the append.
3. **End-and-continue handoff** — `POST
/api/v1/sessions/:session/end-and-continue`, called by the running
agent, triggers a fresh run and atomically swaps `currentRunId`. Used by
`chat.requestUpgrade()` for version handoffs.

Every triggered run is recorded in the `SessionRun` audit table with a
reason (`initial`, `continuation`, `upgrade`, `manual`).

## Public API surface

### Control plane

- `POST /api/v1/sessions` — create. Idempotent on `(env, externalId)`.
Triggers the first run, returns the session and a session-scoped public
access token. Returns 409 if the upserted row is already closed.
- `GET /api/v1/sessions/:session` — retrieve by friendlyId
(`session_abc...`) or by your own externalId (server disambiguates by
prefix).
- `GET /api/v1/sessions` — list with filters (`type`, `tag`,
`taskIdentifier`, `externalId`, derived `status` ACTIVE/CLOSED/EXPIRED,
created-at range) and cursor pagination. Backed by ClickHouse.
- `PATCH /api/v1/sessions/:session` — update tags / metadata /
externalId.
- `POST /api/v1/sessions/:session/close` — terminate. Idempotent,
hard-blocks new server-brokered writes.
- `POST /api/v1/sessions/:session/end-and-continue` — agent-only handoff
to a fresh run.

### Realtime

- `PUT /realtime/v1/sessions/:session/:io` — initialize a channel.
Returns S2 credentials in headers so high-throughput clients can write
direct to S2.
- `GET /realtime/v1/sessions/:session/:io` — SSE subscribe. Supports
Last-Event-ID resume and an opt-in `X-Peek-Settled: 1` header that
fast-closes the stream when the upstream is already settled
(`trigger:turn-complete`), eliminating long-poll wait on
reconnect-on-reload paths.
- `POST /realtime/v1/sessions/:session/:io/append` — server-side
appends.
- `POST /api/v1/runs/:runFriendlyId/session-streams/wait` — runs wait on
a session stream as a waitpoint, with a race-check to avoid suspending
if data already landed.

### Auth scopes

`sessions` is a new resource type. `read:sessions:{id}`,
`write:sessions:{id}`, `admin:sessions:{id}` flow through the existing
JWT validator. Session-scoped public access tokens minted by the server
replace browser-held trigger-task tokens for chat-style flows — the
browser never sees a run identifier or a run-scoped token in steady
state.

## What's coming after this PR

- **SDK + chat.agent migration**: separate branch, separate PR, ships in
the next `@trigger.dev/sdk` prerelease alongside this server deploy.
Customers using the prerelease `chat.agent` will follow the [upgrade
guide](https://github.com/triggerdotdev/trigger.dev/blob/docs/tri-7532-ai-sdk-chat-transport-and-chat-task-system/docs/ai-chat/upgrade-guide.mdx).
- **Dashboard surfaces**: dedicated agent list, agent playground, agent
view on the run dashboard. Tracking separately.

## Implementation notes

- **Postgres `Session` table**: scalar scoping columns (`projectId`,
`runtimeEnvironmentId`, `environmentType`, `organizationId`) without
FKs, matching the January TaskRun FK-removal decision. Point-lookup
indexes only — list queries go to ClickHouse. Terminal markers
(`closedAt`, `expiresAt`) are write-once.
- **ClickHouse `sessions_v1`**: ReplacingMergeTree, partitioned by
month, ordered by `(org_id, project_id, environment_id, created_at,
session_id)`. Tags indexed via `tokenbf_v1` skip index.
- **`SessionsReplicationService`**: mirrors `RunsReplicationService`
exactly — leader-locked logical replication consumer,
`ConcurrentFlushScheduler`, retry with exponential backoff + jitter,
identical metric shape. Dedicated slot + publication so the two consume
independently.
- **S2 keys**: `sessions/{addressingKey}/{out|in}`. The existing
`runs/{runId}/{streamId}` key format for run-scoped streams is
untouched.
- **Optimistic claim**: `ensureRunForSession` triggers a run upfront
(cheap to cancel if it loses the race), then attempts an `updateMany`
keyed on `currentRunVersion`. Loser cancels its triggered run and reuses
the winner's. No DB lock held across the trigger.

### What did NOT change

Run-scoped `streams.pipe` / `streams.input` and the existing
`/realtime/v1/streams/{runId}/...` routes are unchanged. Sessions are
net-new — not a reshaping of the current streams API.

## Deploy notes

- Set `SESSION_REPLICATION_CLICKHOUSE_URL` and
`SESSION_REPLICATION_ENABLED=1` to enable the replication consumer.
- The `Session` table needs `REPLICA IDENTITY FULL` set on the prod
source DB before the publication is created (same one-time DDL we did
for `TaskRun`). Required for delete events to carry full column values.
- Cross-form authorization on the `GET /api/v1/sessions/:session` loader
(a JWT minted for either form authorizes both URL forms). Action routes
are URL-form-specific, matching how the SDK mints PATs.

## Verification

- Webapp typecheck clean (10/10).
- `apps/webapp/test/sessionsReplicationService.test.ts` — round-trip
tests for insert/update/delete through Postgres logical replication into
ClickHouse via testcontainers.
- Live end-to-end against local dev: create + retrieve (both forms) +
update + close, `.out.initialize` + `.out.append` x2 + `.in.send` +
`.out.subscribe` over SSE, list with all filter combinations +
pagination, `end-and-continue` swap, `X-Peek-Settled` fast-close
(verified in browser via reconnect-on-reload and via curl). Replicated
row lands in ClickHouse within ~1s.
- Multi-round Devin + CodeRabbit review feedback addressed
(read-after-write paths use `prisma` writer, info-leak on auth-routes
masked as 403, peek-settled discriminator parsing fix, etc.).

## Test plan

- [ ] `pnpm run typecheck --filter webapp`
- [ ] `pnpm run test --filter webapp
./test/sessionsReplicationService.test.ts --run`
- [ ] Start the webapp with `SESSION_REPLICATION_CLICKHOUSE_URL` and
`SESSION_REPLICATION_ENABLED=1`. Confirm the slot and publication
auto-create on boot.
- [ ] `POST /api/v1/sessions` and verify the row replicates to
`trigger_dev.sessions_v1` within a couple of seconds.
- [ ] `POST /api/v1/sessions/:id/close`, then confirm `POST
/realtime/v1/sessions/:id/out/append` returns 400.
- [ ] Reuse a closed session's `externalId` on `POST /api/v1/sessions`
and confirm 409.
- [ ] `GET /realtime/v1/sessions/:id/out` with `X-Peek-Settled: 1` after
a turn completes and confirm `X-Session-Settled: true` response header +
immediate close.
2026-04-28 12:35:55 +01:00
..
2026-01-09 11:39:36 +00:00

ClickHouse Table Naming Conventions

The following document is heavily inspired by the Unkey ClickHouse naming conventions.

This document outlines the naming conventions for tables and materialized views in our ClickHouse setup. Adhering to these conventions ensures consistency, clarity, and ease of management across our data infrastructure.

General Rules

  1. Use lowercase letters and separate words with underscores.
  2. Avoid ClickHouse reserved words and special characters in names.
  3. Be descriptive but concise.

Table Naming Convention

Format: [prefix]_[domain]_[description]_[version]

Prefixes

  • raw_: Input data tables
  • tmp_{yourname}_: Temporary tables for experiments, add your name, so it's easy to identify ownership.

Versioning

  • Version numbers: _v1, _v2, etc.

Aggregation Suffixes

For aggregated or summary tables, use suffixes like:

  • _per_day
  • _per_month
  • _summary

Materialized View Naming Convention

Format: [description]_[aggregation]_mv_[version]

  • Always suffix with mv_[version]
  • Include a description of the view's purpose
  • Add aggregation level if applicable

Examples

  1. Raw Data Table: raw_sales_transactions_v1

  2. Materialized View: active_users_per_day_mv_v2

  3. Temporary Table: tmp_eric_user_analysis_v1

  4. Aggregated Table: sales_summary_per_hour_mv_v1

Maintain consistent naming across related tables, views, and other objects:

  • raw_user_activity_v1
  • user_activity_per_day_v1
  • user_activity_per_day_mv_v1

By following these conventions, we ensure a clear, consistent, and scalable naming structure for our ClickHouse setup.