ddfe630757
refactor(chatd): replace fantasy.Agent with custom agent loop ( #22507 )
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## Summary
Replaces fantasy's `Agent` abstraction with a direct step loop calling
`LanguageModel.Stream()`. Fantasy is retained as the provider
abstraction layer (streaming parsers, types, tool schema) but we no
longer use `fantasy.Agent`, `AgentStreamCall`, `AgentResult`, or
`StepResult`.
## Problems solved
| Problem | Before | After |
|---|---|---|
| **Sentinel prompt hack** | fantasy.Agent requires non-empty Prompt →
UUID sentinel generated and stripped in PrepareStep | Messages passed
directly to `model.Stream()` |
| **Discarded PersistStep errors** | `_ = opts.OnStepFinish(result)`
silently swallows errors | Errors propagate directly from
`PersistStep()` |
| **Shadow draft state** | ~160 LOC tracking content in parallel because
fantasy doesn't expose in-progress content on interruption |
`stepResult` owns content directly; `flushActiveState()` is trivial |
| **Nested retry layers** | fantasy's 2-attempt retry nested inside
chatretry's indefinite retry | Single `chatretry.Retry` layer |
| **Callback-mediated compaction** | Mutex + boolean flag + coordination
between OnStepFinish/PrepareStep callbacks | Inline `if` statement
between steps |
| **Duplicate compaction paths** | `compactStep()` + `maybeCompact()`
sharing ~80% logic | Single `tryCompact()` function |
## Changes
### `coderd/chatd/chatloop/chatloop.go` — Rewritten
- **Removed**: `fantasy.NewAgent()`, `AgentStreamCall`, sentinel prompt,
shadow draft state (~160 LOC of closures), `compactedMu`/`compacted`
flag, `PrepareStepResult`
- **Added**: `stepResult` struct, `processStepStream()` (stream
consumer), `executeTools()` (sequential tool execution),
`flushActiveState()` (interrupt handling), `buildToolDefinitions()`,
`toResponseMessages()`
- **Changed**: `Run()` return type from `(*fantasy.AgentResult, error)`
to `error` (callers already discarded the result)
- **Preserved**: Anthropic prompt caching, reasoning title extraction,
`extractContextLimit()`, `ErrInterrupted` semantics
### `coderd/chatd/chatloop/compaction.go` — Simplified
- Merged `compactStep()` + `maybeCompact()` → single `tryCompact()`
- Removed `[]StepResult` parameter from `generateCompactionSummary()`
(caller provides complete message list)
- Kept helper functions: `normalizedCompactionConfig`,
`contextTokensFromUsage`, `resolveContextLimit`, `shouldCompact`
### `coderd/chatd/chatd.go` — Caller updates
- Removed `AgentStreamCall` construction
- Changed `_, err = chatloop.Run(...)` to `err = chatloop.Run(...)`
- Model parameters moved from `AgentStreamCall` fields to `RunOptions`
fields
### Tests — 4 new tests
- `MidLoopCompactionReloadsMessages` — compaction fires mid-loop,
messages reloaded
- `PostRunCompactionSkippedAfterMidLoop` — no double compaction
- `MultiStepToolExecution` — tools execute between steps, results feed
next step
- `PersistStepErrorPropagates` — persistence errors propagate (was
silently discarded)
2026-03-02 18:51:57 -05:00
2bdacae5f5
feat(chatd): add LLM stream retry with exponential backoff ( #22418 )
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## Summary
Adds automatic retry with exponential backoff for transient LLM errors
during chat streaming and title generation. Inspired by
[coder/mux](https://github.com/coder/mux )'s retry mechanism.
## Key Behaviors
- **Infinite retries** with exponential backoff: 1s → 2s → 4s → ... →
60s cap
- **Deterministic delays** (no jitter)
- **Error classification**: retryable (429, 5xx, overloaded, rate limit,
network errors) vs non-retryable (auth, quota, context exceeded, model
not found, canceled)
- **Retry status published to SSE stream** so frontend can show
"Retrying in Xs..." UI
- **Title generation** retries silently (best-effort, nil onRetry
callback)
## New Package: `coderd/chatd/chatretry/`
| File | Purpose |
|------|---------|
| `classify.go` | `IsRetryable(err)` and `StatusCodeRetryable(code)` |
| `backoff.go` | `Delay(attempt)` — exponential doubling with 60s cap |
| `retry.go` | `Retry(ctx, fn, onRetry)` — infinite loop with
context-aware timer |
## Test Helpers: `coderd/chatd/chattest/errors.go`
Anthropic and OpenAI error response builders for use in chattest
providers:
- `AnthropicErrorResponse()`, `AnthropicOverloadedResponse()`,
`AnthropicRateLimitResponse()`
- `OpenAIErrorResponse()`, `OpenAIRateLimitResponse()`,
`OpenAIServerErrorResponse()`
## SDK Changes: `codersdk/chats.go`
- New `ChatStreamEventType: "retry"`
- New `ChatStreamRetry` struct with `Attempt`, `DelayMs`, `Error`,
`RetryingAt` fields
- TypeScript types auto-generated
## Changed Files
- `coderd/chatd/chatloop/chatloop.go` — wraps `agent.Stream()` in
`chatretry.Retry()`
- `coderd/chatd/chatd.go` — publishes retry events to SSE stream with
logging
- `coderd/chatd/title.go` — wraps `model.Generate()` in silent retry
- `coderd/chatd/chattest/anthropic.go` / `openai.go` — error injection
support
## Tests
42 tests covering classification (33), backoff (9), and retry scenarios
(8).
2026-02-27 18:34:33 -05:00
360df1d84f
fix(chatd): publish streaming message_part events during compaction ( #22410 )
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## Problem
Context compaction in chatd persisted durable messages for the
`chat_summarized` tool call and result via `publishMessage`, but never
published `message_part` streaming events via `publishMessagePart`. This
meant connected clients had no streaming representation of the
compaction.
The client's `streamState` (built entirely from `message_part` events in
`streamState.ts`) never saw the compaction tool call, so:
- No **"Summarizing..."** running state was shown to the user during
summary generation (which can take up to 90s).
- The durable `message` events arrived after or interleaved with the
`status: waiting` event, causing the tool to appear as "Summarized" with
the chat appearing to just stop.
## Fix
### 1. `CompactionOptions.OnStart` callback (chatloop)
Added an `OnStart` callback to `CompactionOptions`, called in
`maybeCompact` right before `generateCompactionSummary` (the slow LLM
call). This gives `chatd` a hook to publish the tool-call `message_part`
immediately when compaction begins.
### 2. Tool-result streaming part (chatd)
`persistChatContextSummary` now publishes a tool-result `message_part`
before the durable `message` events, so clients transition from
"Summarizing..." to "Summarized" before the status change arrives.
### Event ordering is now:
1. `message_part` (tool call via `OnStart`) — client shows
"Summarizing..."
2. LLM generates summary (up to 90s)
3. `message_part` (tool result) — client shows "Summarized" in stream
state
4. `message` (assistant) — durable message persisted, stream state
resets
5. `message` (tool) — durable tool result persisted
6. `status: waiting` — chat transitions to idle
## Tests
- **`OnStartFiresBeforePersist`**: Verifies callback ordering is
`on_start` → `generate` → `persist`.
- **`OnStartNotCalledBelowThreshold`**: Verifies `OnStart` is not called
when context usage is below the compaction threshold.
2026-02-27 16:33:39 -05:00
edee917d88
feat: add experimental agents support ( #22290 )
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feat: add AI chat system with agent tools and chat UI
Introduce the chatd subsystem and Agents UI for AI-powered chat
within Coder workspaces.
- Add chatd package with chat loop, message compaction, prompt
management, and LLM provider integration (OpenAI, Anthropic)
- Add agent tools: create workspace, list/read templates, read/write/
edit files, execute commands
- Add chat API endpoints with streaming, message editing, and
durable reconnection
- Add database schema and migrations for chats, chat messages, chat
providers, and chat model configs
- Add RBAC policies and dbauthz enforcement for chat resources
- Add Agents UI pages with conversation timeline, queued messages
list, diff viewer, and model configuration panel
- Add comprehensive test coverage including coderd integration tests,
chatd unit tests, and Storybook stories
- Gate feature behind experiments flag
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Co-authored-by: Cian Johnston <cian@coder.com >
Co-authored-by: Danielle Maywood <danielle@themaywoods.com >
Co-authored-by: Jeremy Ruppel <jeremy@coder.com >
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com >
2026-02-27 16:50:56 +00:00
Kyle Carberry