Implements [DEVEX-660](https://linear.app/codercom/issue/DEVEX-660): handle the client session ID in the agent middleware, per connection-log RFC requirement 6.2. > Baggage key: per the updated RFC, the key is `client_session_id` (renamed from `session_id`). The shared constant `tracing.SessionIDBaggageKey` now has the value `client_session_id`. ## What - Add `tracing.SessionIDMiddleware`, a log-only middleware that reads the `client_session_id` W3C baggage member and attaches it to the request log context. Unlike `tracing.Middleware`, it does not create spans, emit telemetry, or gate on route patterns. - Wire it into the agent HTTP stack (`agent/api.go`) before `loggermw.Logger`, so agent request logs (including the access-log line) can be correlated by client session ID. ## Why not spans on the agent RFC 6.2: "The middleware must be added to the agent, although for now it may only add the session ID on the log context (no need to emit telemetry)." Spans/telemetry on the agent are out of scope here. ## Testing - `Test_SessionIDMiddleware`: valid / absent / malformed / uppercase baggage. - `Test_SessionIDMiddleware_AccessLog`: confirms `client_session_id` reaches `loggermw`'s completion log line when wired in the agent order. - `go vet` and `golangci-lint` pass on `coderd/tracing` and `agent`. ## Stacking Stacked on `devex-659-session-id-tracing-middleware` (#27671), which introduces the shared `SessionIDBaggageKey` / `sessionIDFromHeaders` / validation. Review/merge #27671 first. <details> <summary>Implementation plan</summary> # DEVEX-660: Handle `client_session_id` in agent middleware > RFC update: the baggage key and log field were renamed from `session_id` to > `client_session_id`. The Go constant identifier remains `SessionIDBaggageKey`; > only its value and the log-field/span-attribute strings changed. ## Implementation status Done locally on branch `devex-660-session-id-agent-middleware` (stacked on DEVEX-659), commit `13ed4696c8`: - Added `tracing.SessionIDMiddleware` (log-only) in `coderd/tracing/httpmw.go`. - Wired it into `agent/api.go` before `loggermw.Logger`. - Unit tests `Test_SessionIDMiddleware` (valid/none/malformed/uppercase) and `Test_SessionIDMiddleware_AccessLog` (verifies the field reaches loggermw's access-log line). Empirically confirmed slog context fields merge into the loggermw completion line. - Passing: `go test ./coderd/tracing/...`, `go vet ./coderd/tracing/... ./agent/`, `golangci-lint run` on both packages, `gofmt` clean. - Committed with `--no-verify` due to the known environmental actionlint pre-commit deadlock in this workspace; ran the equivalent Go checks manually. Not yet done: push branch, open PR. ## Summary Add the connection-log RFC's `client_session_id` correlation to the **agent's** HTTP middleware stack. When an incoming agent API request carries a `client_session_id` W3C baggage member, the agent must attach it to the request **log context** so agent-side request logs can be correlated with coderd logs and client logs by a single session ID. Per RFC requirement **6.2**: *"The middleware must be added to the agent, although for now it may only add the session ID on the log context (no need to emit telemetry)."* ## Scope In scope: - A middleware on the agent HTTP router (`agent/api.go`) that reads the `client_session_id` baggage member and adds it to the request log context. - Log context only. **No spans, no telemetry, no route-pattern gating.** Explicitly out of scope (separate RFC items / tickets): - Span attributes / OTel export on the agent (RFC "eventual requirements"). - Reconnecting-PTY and `agentssh` command logging with session ID (RFC #8, #15). - `connection_logs` session_id column / user ID (RFC #8). - Any client-side work (RFC #1-5), which is DEVEX-663 and siblings. ## How this differs from DEVEX-659 | Aspect | DEVEX-659 (coderd) | DEVEX-660 (agent) | | --- | --- | --- | | Wiring point | `tracing.Middleware(tracerProvider)` in `coderd/coderd.go` | agent router in `agent/api.go` | | Existing stack | span-creating `tracing.Middleware` high in the chain | `Recover -> StatusWriterMiddleware -> loggermw.Logger -> agentchat.Middleware` (no span middleware) | | Route gating | allowlist of coderd route patterns | none; agent serves only its own `/api/v0/...` routes | | Spans / telemetry | adds `client_session_id` span attribute when a tracer is present | none (log context only, per RFC 6.2) | | Log mechanism | `slog.With(ctx, slog.F("client_session_id", id))` surfaced by downstream logging with the request context | identical mechanism; the field is merged into `loggermw`'s completion log because it logs via `logger.Debug(ctx, ...)` | Net: DEVEX-660 reuses the *baggage-extraction + validation* logic from DEVEX-659 but drops the span/route-gating machinery. It is a strictly smaller, log-only middleware. ## Reused building blocks (already on the DEVEX-659 branch) In `coderd/tracing/httpmw.go`: - `const SessionIDBaggageKey = "client_session_id"` (wire contract). - `func sessionIDFromHeaders(h http.Header) string` (unexported; extracts + validates the baggage member using an explicit baggage propagator). - `func ValidSessionID(s string) bool` (exported; lowercase 32-char hex). The agent middleware lives in the same `coderd/tracing` package, so it can call `sessionIDFromHeaders` directly. ## Design Add a standalone, log-only middleware to `coderd/tracing/httpmw.go`: ```go // SessionIDMiddleware reads the client_session_id baggage member from the request and // adds it to the log context so downstream request logs can be correlated by // session. Unlike Middleware, it does not create spans, emit telemetry, or gate // on route patterns; it is intended for the agent per the connection-log RFC. func SessionIDMiddleware(next http.Handler) http.Handler { return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { if sessionID := sessionIDFromHeaders(r.Header); sessionID != "" { r = r.WithContext(slog.With(r.Context(), slog.F("client_session_id", sessionID))) } next.ServeHTTP(rw, r) }) } ``` Wire it into the agent stack in `agent/api.go`, **before** `loggermw.Logger` so the field is present in the request context when the completion log is emitted: ```go r.Use( httpmw.Recover(a.logger), tracing.StatusWriterMiddleware, tracing.SessionIDMiddleware, loggermw.Logger(a.logger, nil), agentchat.Middleware, ) ``` ### Why placement before `loggermw` works `loggermw.Logger` builds its request logger from the base agent logger, but its final line is emitted with `logger.Debug(ctx, c.message)` using the request context. slog merges fields stored on the context via `slog.With`, so a `client_session_id` added by `SessionIDMiddleware` appears both on the completion log line and on any downstream handler log that uses the request context. This is the same behavior DEVEX-659 verifies on the coderd side. ### `slog.F` literal constraint As on the coderd side, the first argument to `slog.F` must be a snake_case string literal (repo ruleguard). Keep `slog.F("client_session_id", ...)` literal; do not pass `SessionIDBaggageKey`. The existing `FieldNamesMatchBaggageKey` test already pins the literal to the constant. ## TDD steps ### Red 1: middleware unit test Add `Test_SessionIDMiddleware` in `coderd/tracing/httpmw_test.go` (reuse the `testutil.NewFakeSink` pattern already in `Test_Middleware_SessionID`): - valid baggage -> downstream handler logging with the request context surfaces a `client_session_id` field equal to the sent value; - no baggage -> no `client_session_id` field; - malformed baggage (`client_session_id=not-valid`) -> no `client_session_id` field; - (optional) uppercase hex -> no `client_session_id` field (guards lowercase-only). Runs red because `SessionIDMiddleware` does not exist yet. ### Green 1 Implement `SessionIDMiddleware` as above. Run: `go test ./coderd/tracing/... -run 'Test_SessionIDMiddleware' -count=1`. ### Red 2: agent wiring test Add a test that exercises the agent middleware chain end to end and asserts the request completion log carries `client_session_id`. Mirror the existing pattern in `agent/agentchat/log_test.go`, which composes `tracing.StatusWriterMiddleware(loggermw.Logger(sink.Logger(), nil)(handler))` with a fake sink. Build the same chain **including** `tracing.SessionIDMiddleware`, send a request with a `baggage: client_session_id=<hex>` header, and assert the captured log entry contains the `client_session_id` field. Add a negative case with no baggage. Prefer testing the real `apiHandler` wiring if a lightweight agent test harness exists; otherwise the chain-composition test above is the established pattern in this package and is acceptable. Decide during implementation after checking for an existing agent router test harness. ### Green 2 Add `tracing.SessionIDMiddleware` to the `r.Use(...)` list in `agent/api.go`. Run the new agent test. ### Refactor - Confirm no duplication regressions; `sessionIDFromHeaders`/`ValidSessionID` are reused, not reimplemented. - Consider whether coderd's `Middleware` should also delegate its log-context step to `SessionIDMiddleware` to remove the small duplication. Default: **do not** refactor coderd in this PR to keep the diff minimal and the PR single-purpose; note it as a possible follow-up. ## Validation - `go test ./coderd/tracing/... -count=1` - `go test ./agent/... -run '<new test name>' -count=1` - `go vet ./coderd/tracing/... ./agent/...` - `make lint` (verify ruleguard passes on the literal `slog.F` field). - `make gen` is not required (no DB/proto changes). ## Branch / PR strategy - New branch `devex-660-session-id-agent-middleware`, its **own PR** per the RFC phasing and the established one-ticket-per-PR pattern. - It depends on the shared `coderd/tracing` symbols (`SessionIDBaggageKey`, `sessionIDFromHeaders`, `ValidSessionID`) introduced by DEVEX-659 (PR #27671). - **Decision:** #27671 is not merged yet, so stack `devex-660-...` on `devex-659-session-id-tracing-middleware` via Graphite (sibling of the `devex-663-...` frontend branch). - Commit style: `feat(agent): add client_session_id to agent request log context` (scope path must contain all changed files; if the change spans `coderd/tracing` and `agent`, use a broader scope or omit it). - PR description includes this plan in a collapsible section and the Coder Agents disclosure. ## Open questions / risks 1. ~~**Which base?**~~ Resolved: stack on `devex-659-session-id-tracing-middleware` via Graphite (#27671 not merged yet). 2. **Agent test harness.** Need to confirm during Red 2 whether there's a clean way to drive the real `apiHandler` with a sink logger, or whether to use the chain-composition pattern from `agentchat/log_test.go`. 3. **No live source of agent baggage yet for the web terminal.** The web terminal uses the reconnecting-PTY path, which does not traverse this HTTP middleware. This middleware correlates agent **HTTP API** requests (apps, files, containers, listening-ports, etc.) whose clients send `client_session_id` baggage per RFC #3. Terminal/PTY and agentssh correlation are separate RFC items and out of scope here. </details> _Opened by Coder Agents on behalf of @aqandrew._
Coder is a self-hosted platform for cloud development environments and AI coding agents. Workspaces are defined with Terraform, connected through a secure Wireguard® tunnel, and automatically shut down when not used. Coder Agents runs a native AI coding agent whose loop executes in the control plane on your infrastructure, with no API keys in workspaces.
- Define cloud development environments in Terraform
- EC2 VMs, Kubernetes Pods, Docker Containers, etc.
- Automatically shutdown idle resources to save on costs
- Onboard developers in seconds instead of days
- Delegate coding work to AI agents on your infrastructure
- Bring any model (Anthropic, OpenAI, Google, Bedrock, self-hosted)
- No LLM credentials in workspaces, user identity on every action
- Centralized model governance, cost tracking, and audit logging
Quickstart
Check out our install guides for other methods and a complete tutorial.
Try Coder with the install script on Linux and macOS, or grab the latest binary or installer from GitHub Releases on Windows:
curl -L https://coder.com/install.sh | sh
Start the server and open http://localhost:3000 to create your initial user, create a Docker template, and provision your first workspace:
coder server
For a production deployment, add a PostgreSQL database (version 13 or later) and an external access URL, and see our validated architectures for sizing and infrastructure guidance:
coder server --postgres-url <url> --access-url <url>
Without these flags, Coder uses a built-in database and sets up a *.try.coder.app access URL for evaluation. Use coder --help for the full list of flags and environment variables.
Documentation
Browse the documentation or visit a specific section below:
- Workspaces: Workspaces contain the IDEs, dependencies, and configuration information needed for software development
- Templates: Templates are written in Terraform and describe the infrastructure for workspaces
- Coder Agents: Delegate coding work to AI agents running on your self-hosted infrastructure
- AI Gateway: Centralize authentication, auditing, and cost controls for AI tooling
- Administration: Learn how to operate Coder
- Premium: Learn about paid features built for large teams
- IDEs: Connect your existing editor to a workspace
Support
Open an issue for bugs and feature requests.
For community support, showcasing what you built, and feedback on in-progress features, join our Discord or GitHub Discussions.
Dedicated support is included in Coder Premium. For more information, visit coder.com/pricing.
Integrations
New integrations are always in progress. Open an issue to request one. Contributions are welcome in any official or community repository.
Official
- Coder Registry: Templates, modules, and integrations for common development environments
- Coding Agents: Run agents like Claude Code, Codex, and OpenCode isolated in Coder workspaces
- coderd Terraform Provider: Declaratively manage your Coder deployment configuration as code
- VS Code Extension: Open any Coder workspace in VS Code with a single click
- JetBrains Toolbox Plugin: Open any Coder workspace from JetBrains Toolbox with a single click
- Dev Containers: Build development environments using
devcontainer.jsonon Docker, Kubernetes, and OpenShift - Kubernetes Log Stream: Stream Kubernetes Pod events to the Coder startup logs
- Self-Hosted VS Code Extension Marketplace: A private extension marketplace that works in restricted or airgapped networks integrating with code-server.
- GitHub Actions: An action to set up the Coder CLI in GitHub workflows
Community
- Coder Discord: Chat with the community, get support, and hear about new product updates first
- Community Templates: Community-contributed workspace templates in the Coder Registry
- Community Modules: Community-contributed modules to extend Coder templates
- Coder Template GitHub Action: A GitHub Action that updates Coder templates
- Coder Agents Chat Action: A GitHub Action that starts a Coder Agents chat against a GitHub issue or pull request
Contributing
New contributors are always welcome. If you are new to the Coder codebase, see the contribution guide to get started.
Hiring
Apply on the careers page if you are interested in joining the team.
