kandev/apps/backend/AGENTS.md

Backend (Go) — architecture and conventions

Scoped guidance for apps/backend/. Repo-wide rules (commit format, code-quality limits, etc.) live in the root AGENTS.md.

Package Structure

apps/backend/
├── cmd/
│   ├── kandev/           # Main backend binary entry point
│   ├── agentctl/         # Agentctl binary (runs inside containers or standalone)
│   └── mock-agent/       # Mock agent for testing
├── internal/
│   ├── agent/
│   │   ├── runtime/      # Agent runtime: single seam for Launch/Resume/Stop/observe
│   │   │   ├── lifecycle/    # Agent instance management (moved from agent/lifecycle)
│   │   │   ├── agentctl/     # HTTP client for talking to agentctl (moved from agentctl/client)
│   │   │   └── routingerr/   # Provider error classifier + sanitizer + ProviderProber registry
│   │   ├── agents/       # Agent type implementations
│   │   ├── controller/   # Agent control operations
│   │   ├── credentials/  # Agent credential management
│   │   ├── discovery/    # Agent discovery
│   │   ├── docker/       # Docker-specific agent logic
│   │   ├── dto/          # Agent data transfer objects
│   │   ├── executor/     # Executor types, checks, and service
│   │   ├── handlers/     # Agent event handlers
│   │   ├── registry/     # Agent type registry and defaults
│   │   ├── settings/     # Agent settings
│   │   ├── mcpconfig/    # MCP server configuration
│   │   └── remoteauth/   # Remote auth catalog and method IDs for remote executors/UI
│   ├── agentctl/
│   │   └── server/       # agentctl HTTP server
│   │       ├── acp/      # ACP protocol implementation
│   │       ├── adapter/  # Protocol adapters + transport/ (ACP, Codex, OpenCode, Copilot, Amp)
│   │       ├── api/      # HTTP endpoints
│   │       ├── config/   # agentctl configuration
│   │       ├── instance/ # Multi-instance management
│   │       ├── mcp/      # MCP server integration
│   │       ├── process/  # Agent subprocess management
│   │       ├── shell/    # Shell session management
│   │       └── utility/  # agentctl utilities
│   ├── orchestrator/     # Task execution coordination
│   │   ├── dto/          # Orchestrator data transfer objects
│   │   ├── executor/     # Launches agents via lifecycle manager
│   │   ├── handlers/     # Orchestrator event handlers
│   │   ├── messagequeue/ # Message queue for agent prompts
│   │   ├── queue/        # Task queue
│   │   ├── scheduler/    # Task scheduling
│   │   └── watcher/      # Event handlers
│   ├── task/
│   │   ├── controller/   # Task HTTP/WS controllers
│   │   ├── dto/          # Task data transfer objects
│   │   ├── events/       # Task event types
│   │   ├── handlers/     # Task event handlers
│   │   ├── models/       # Task, Session, Executor, Message models
│   │   ├── repository/   # Database access (SQLite)
│   │   └── service/      # Task business logic
│   ├── office/           # Autonomous agent management (Office feature)
│   │   ├── agents/       # Agent instance CRUD + auth guards
│   │   ├── approvals/    # Approval requests and decisions
│   │   ├── channels/     # External integration channels (webhooks)
│   │   ├── config/       # Config sync (DB ↔ filesystem)
│   │   ├── configloader/ # Filesystem config reader/writer
│   │   ├── costs/        # Cost tracking and budget policies
│   │   ├── dashboard/    # Dashboard API, issues, activity, live runs
│   │   ├── infra/        # GC, reconciliation
│   │   ├── labels/       # Task labels
│   │   ├── onboarding/   # Workspace onboarding wizard API
│   │   ├── projects/     # Project management
│   │   ├── repository/   # Office SQLite persistence
│   │   ├── runtime/      # Agent run context, capabilities, and runtime action surface
│   │   ├── routines/     # Scheduled recurring tasks
│   │   ├── routing/      # Provider routing: resolver, validators, catalogue, backoff, agent-overrides
│   │   ├── scheduler/    # Wakeup scheduler (duplicate of service scheduler features)
│   │   ├── service/      # Core office service (wakeups, event subscribers, execution policy)
│   │   ├── shared/       # Shared interfaces and activity logging
│   │   ├── skills/       # Skill injection and materialization
│   │   └── workspaces/   # Workspace deletion handler
│   ├── events/           # Event bus for internal pub/sub
│   ├── gateway/          # WebSocket gateway
│   ├── github/           # GitHub API integration (PRs, reviews, webhooks)
│   ├── common/           # Shared utilities, config, logger
│   ├── integration/      # External integrations
│   ├── integrations/     # Shared shapes for third-party integrations
│   │   ├── healthpoll/   # Reusable 90s auth-health Poller (used by jira, linear)
│   │   └── secretadapter/ # Upsert-style adapter over secrets.SecretStore
│   ├── jira/             # Jira/Atlassian Cloud integration (config, REST client, poller)
│   ├── linear/           # Linear integration (config, GraphQL client, poller)
│   ├── lsp/              # LSP server
│   ├── mcp/              # MCP protocol support
│   ├── health/           # Health check endpoints
│   ├── notifications/    # Notification system
│   ├── persistence/      # Persistence layer
│   ├── prompts/          # Prompt management
│   ├── repoclone/        # Repository cloning for remote executors
│   ├── scriptengine/     # Script placeholder resolution and interpolation
│   ├── secrets/          # Secret management
│   ├── sprites/          # Sprites AI integration
│   ├── sysprompt/        # System prompt injection
│   ├── tools/            # Tool integrations
│   ├── user/             # User management
│   ├── utility/          # Shared utility functions
│   ├── workflow/         # Workflow engine
│   │   ├── engine/       # Typed state-machine engine
│   │   ├── models/       # Workflow step, template, and history models
│   │   ├── repository/   # Workflow persistence (SQLite)
│   │   └── service/      # Workflow CRUD and step resolution
│   └── worktree/         # Git worktree management for workspace isolation

Key Concepts

Orchestrator coordinates task execution:

• Receives task start/stop/resume requests via WebSocket
• Delegates to lifecycle manager for agent operations
• Handles event-driven state transitions via workflow engine
• Located in internal/orchestrator/

Watcher Dispatch Coordinator (internal/orchestrator/watcher_dispatch.go) is the single pipeline that turns a freshly-observed external issue (Linear, Jira, future) into a Kandev task. Bus subscribers for each integration forward the event to WatcherDispatchCoordinator.Dispatch with a per-integration WatcherSource implementation (source_linear.go, source_jira.go). Source methods carry the integration-specific bits (reserve dedup, build task request, attach task ID, release, auto-start params); the coordinator owns the cross-cutting pipeline (create task, decide auto-start, error/release handling). Add a new watcher = implement WatcherSource + register a one-line bus subscriber. Do NOT add another createXIssueTask mirror.

Workflow Engine (internal/workflow/engine/) provides typed state-machine evaluation:

• Engine.HandleTrigger() evaluates step actions for triggers (on_enter, on_turn_start, on_turn_complete, on_exit)
• TransitionStore interface abstracts persistence (implemented by orchestrator.workflowStore)
• CallbackRegistry maps action kinds to callbacks (plan mode, auto-start, context reset)
• First-transition-wins: multiple transition actions in one trigger, first eligible wins
• EvaluateOnly mode: engine evaluates without persisting, caller orchestrates on_exit → DB → on_enter
• RequiresApproval on actions: transitions requiring review gating are skipped
• Idempotent by OperationID; session-scoped data bag via MachineState.Data

Agent Runtime (internal/agent/runtime/) is the single seam for launching, resuming, stopping, and observing agent executions. ADR 0004 introduced this in Phase 1 of task-model-unification. The public surface is runtime.Runtime (runtime.go); a thin facade (facade.go) delegates to a Backend (satisfied by *lifecycle.Manager).

Convention: only internal/agent/runtime/ (and code that pre-dates Phase 1 migration) may import runtime/lifecycle or runtime/agentctl directly. New consumers — workflow engine actions, cron-driven trigger handlers, future task-tier callers — should depend on runtime.Runtime. Existing call sites are migrated through later phases of task-model-unification.

Lifecycle Manager (internal/agent/runtime/lifecycle/) manages agent instances under the runtime:

• Manager (manager.go, manager_*.go) - central coordinator for agent lifecycle
• ExecutorBackend interface (executor_backend.go) - abstracts execution environment (Docker, Standalone, Sprites, Remote Docker)
• ExecutionStore (execution_store.go) - thread-safe in-memory execution tracking
• session.go - ACP session initialization and resume
• streams.go - WebSocket stream connections to agentctl
• process_runner.go - agent process launch and management
• profile_resolver.go - resolves agent profiles/settings

agentctl client (internal/agent/runtime/agentctl/) is the HTTP/WS client used by the lifecycle manager to talk to a running agentctl instance. It is a runtime-tier package and should not be imported outside internal/agent/runtime/.

agentctl is an HTTP server that:

• Runs inside Docker containers or as standalone process
• Manages agent subprocess via stdin/stdout (ACP protocol)
• Exposes workspace operations (shell, git, files)
• Supports multiple concurrent instances on different ports

Standalone agentctl is launched in its own process group so terminal Ctrl+C is handled by the backend lifecycle manager first. Do not make standalone agentctl share the backend's foreground process group; that bypasses supervised shutdown and can leak ACP subprocesses.

Executor Types (database model):

• local_pc - Standalone process on host
• local_docker - Docker container on host
• sprites - Sprites cloud environment
• remote_docker, remote_vps, k8s - Planned

Remote SSH executor platforms: Treat supported remote OS/arch values as an end-to-end contract. Platform probe/normalization, lifecycle support checks, agentctl helper resolution, platform default shell, SSH readiness endpoints, frontend response types, and tests must stay aligned. Preserve raw unsupported platform details in user-facing errors, but use normalized values for supported-platform matching. Keep shell defaults platform-aware: Darwin defaults to zsh, Linux defaults to bash, unless an explicit shell is saved.

Execution Flow

Client (WS) → Orchestrator → Lifecycle Manager → ExecutorBackend (container/process) → agentctl
                                                                                          ↓
Client (WS) ← Orchestrator ← Lifecycle Manager ←──── stream updates (WS) ──────── agent subprocess

1. Orchestrator receives session.launch via WS
2. Lifecycle Manager creates executor instance (container or process)
3. agentctl starts inside the instance, agent subprocess is configured and started
4. Agent events stream back via WS through the chain

Session Resume: TaskSession.ACPSessionID stored for resume; ExecutorRunning tracks active state; on restart RecoverInstances() reconnects.

Provider Pattern: Packages expose Provide(cfg, log) (*impl, cleanup, error) for DI. Returns implementation, cleanup function, and error. Cleanup called during graceful shutdown.

Worktrees: internal/worktree/Manager provides workspace isolation. Each session can have its own worktree (branch) to prevent conflicts between concurrent agents.

Worktree file materialization: copy_files (Repository.CopyFiles) is a single comma-separated spec of gitignored files/globs seeded into each new worktree. Each entry may carry an optional :keyword suffix; the only keyword is :symlink (e.g. .env.local:symlink), which links the entry back to the main repo instead of copying it so shared files stay centralized. No suffix = copy (the default, fully backward compatible). Parsing, validation, and materialization live in internal/worktree/copyfiles/ (ParseSpecs → []PatternSpec{Pattern, Symlink}, ValidateSpec gates unknown keywords at save time, Copy honors symlink mode host-side). Manager.copyConfiguredFiles (in manager_lifecycle.go) runs it during worktree creation. Non-fatal: per-entry failures become warnings. Symlinks use relative targets (unix/macOS) and only apply on the host path — the remote-executor path (Plan/WriteEntries) strips the keyword and falls back to a byte copy, since a link back to the host repo can't apply remotely.

Executor default scripts: Default prepare scripts are in internal/agent/runtime/lifecycle/default_scripts.go; internal/scriptengine/ handles placeholder resolution.

Conventions

• Provider pattern for DI; stderr for logs, stdout for ACP only.
• Pass context through chains; event bus for cross-component comm.
• Execution access: Workspace-oriented handlers (files, shell, inference, ports, vscode, LSP) MUST use GetOrEnsureExecution(ctx, sessionID) — it recovers from backend restarts by creating executions on-demand. Only use GetExecutionBySessionID for operations that require a running agent process (prompt, cancel, mode).
• Task lifecycle events: Any code path that mutates a task row must publish via the event bus (task.created / task.updated / task.deleted) — either by going through Service.CreateTask / UpdateTask / DeleteTask / ArchiveTask, or by calling publishTaskEvent (or one of the Publish* helpers in service_events.go) directly. Walking repository.TaskRepository straight bypasses event publishing and breaks WS-driven UI like the All-Workflows kanban view. HandoffService's cascade methods learned this the hard way — they now require a TaskEventPublisher wired via SetTaskEventPublisher. New cascade / bulk / cleanup paths must follow the same pattern.
• Testing: Prefer testing/synctest (Go 1.24+) over time.Sleep for time-dependent tests. Use synctest.Test to wrap tests with tickers or timeouts — it advances fake time instantly when all goroutines are idle. When synctest is not feasible (e.g., tests spawning external processes like git), use channel-based synchronization (<-started, non-blocking select) instead of sleep-based waits. Reserve time.Sleep only for integration tests that need real subprocess execution time.
  • Test cleanup: Register t.Cleanup immediately after creating resources that need teardown (adapters, io.Pipe writers, background goroutines) — before any t.Fatal/t.Fatalf path. Late cleanup registration leaks pipes and goroutines on early failure.
  • Joining production goroutines in tests: When code spawns untracked goroutines (e.g. fireWakeup), don't rely on arbitrary sleeps. Join via an observable side effect — e.g. block on EventTypeComplete from a.updatesCh after unblocking the fake agent. Use short timeouts (~100ms) for in-process negative assertions; reserve multi-second waits for subprocess/integration tests only.
  • Path/security tests: Avoid using the real filesystem root as a fixture root. Build fake absolute roots under t.TempDir() with filepath.Join; this keeps tests portable across Windows, POSIX, and privileged cloud executors.
  • Filesystem permission tests: Assert permission-denied behavior only after probing that the current executor enforces the permission bit change. Root-like Sprite executors may bypass chmod restrictions.
  • Full test output: For local full-suite pass/fail validation, prefer plain go test -race ./.... go test -json ./... can emit very large JSONL streams; if a wrapper or tracing tool truncates the stream mid-record, downstream JSON parsing may fail even when Go tests passed. Use JSON output mainly for CI artifacts or test-report tooling that explicitly requires it.

Goroutine ownership and leak testing

Every long-running goroutine must have a single owner with explicit start and stop semantics:

• Lifecycle: the type that spawns the goroutine also exposes Start(ctx) / Stop() (or equivalent). Start registers on a sync.WaitGroup; Stop cancels the goroutine's context (or closes a stopCh) and wg.Wait()s for drain. Idempotent on both ends. internal/integrations/healthpoll, internal/jira, internal/linear, and internal/github pollers are the canonical shape.
• E2E reset invariant: seedData/backend are worker-scoped, so any workspace-scoped state a global poller reads (for example github_review_watches) must be deleted in cmd/kandev/e2e_reset.go before task deletion — otherwise the poller recreates rows mid-reset and later tests see duplicates. Add a Delete...ByWorkspace cascade when introducing a new poller-backed entity.
• Cancellation: the goroutine selects on ctx.Done() (or stopCh) in every long wait. Never use time.Sleep in a retry/backoff loop — use time.NewTimer inside a select that also watches the shutdown signal (see lifecycle.StreamManager.sleepOrStop).
• Detached helpers: event handlers and short-lived go func() calls in internal/orchestrator/ and internal/agent/runtime/lifecycle/ must accept a cancellable context (or check the owning type's shutdown signal) and return promptly when it fires.
• Leak testing: packages that spawn goroutines add goleak.VerifyTestMain(m) in a per-package TestMain. New packages of this kind must follow suit. When a third-party background goroutine genuinely can't be drained, suppress it with goleak.IgnoreTopFunction(...) and leave a comment explaining why. Currently instrumented: internal/gateway/websocket/, internal/agent/runtime/lifecycle/, internal/agentctl/server/process/, internal/orchestrator/, internal/github/, internal/jira/, internal/linear/, internal/integrations/healthpoll/.

Backups

• On every SQLite boot, persistence.Provide reads kandev_meta.kandev_version. If the stored version differs from the binary version (or any user tables exist but no version is recorded), it takes a VACUUM INTO snapshot into <data-dir>/backups/ before running migrations.
• Retention: 2 backups kept (newest two by mtime); older ones are pruned after the snapshot succeeds.
• Postgres: backup is skipped with a log line. Use pg_dump for Postgres backups.
• Boot aborts if the backup fails — the pool is closed and Provide returns an error.
• After all repos complete initSchema, cmd/kandev/storage.go:recordSchemaVersion writes the current binary version into kandev_meta (non-fatal; a failure just means the next boot will take a fresh snapshot).
• Migration logging: db.MigrateLogger.Apply(name, stmt) — success logs Info, "already exists" / "duplicate column name" is silently swallowed, anything else logs Warn but never returns an error (preserving the existing swallow-error contract).
• Schema replay handling: use internal/db helpers such as IsDuplicateColumnError / IsAlreadyExistsError instead of local error-string matching. When adding or changing startup schema code, include fresh-DB plus same-DB replay tests for SQLite; add the same env-gated Postgres replay coverage when the path supports Postgres. See docs/decisions/0027-replayable-schema-migrations.md.

Schema & migrations (SQLite repository)

initSchema() in internal/task/repository/sqlite/base_schema.go runs the init*Schema (CREATE TABLE) steps before runMigrations(). The table-creation DDL uses CREATE TABLE IF NOT EXISTS, so on an existing database it is a no-op and never adds columns to a table that is already present.

Rule: when you add a column to an existing table, add it only via an idempotent ADD COLUMN migration in runMigrations() (base_migrations.go), never by editing the table's CREATE TABLE alone. Anything that references that new column — an index, a backfill UPDATE, a partial-index predicate — must live in runMigrations() after the ADD COLUMN, not in the init*Schema DDL. Putting a CREATE INDEX ... (new_col) in the schema-init block crashes existing DBs with no such column: new_col, because schema init runs before the migration that adds the column.

You may still list the column in the CREATE TABLE so fresh DBs get it inline, but the migration is the source of truth for evolution and must stand alone. New columns also need: the struct field in models/, the DTO field + ToAPI in pkg/api/v1/, and every CreateX/UpdateX/bulk write in the repo that should set it.

Code-quality limits

Enforced by apps/backend/.golangci.yml (errors on new code only):

• Functions: ≤80 lines, ≤50 statements
• Cyclomatic complexity: ≤15 · Cognitive complexity: ≤30
• Nesting depth: ≤5 · Naked returns only in functions ≤30 lines
• No duplicated blocks (≥150 tokens) · Repeated strings → constants (≥3 occurrences)

When you hit a limit, extract a helper function. Prefer composition over growing a single function.

When a PR fixup touches backend code, run the CI-style changed-file linter locally from apps/backend with the PR base SHA before pushing, because CI enforces changed-file complexity thresholds:

golangci-lint run ./... --new-from-rev="<base-sha>" --timeout=5m

Further scoped notes

• internal/agentctl/AGENTS.md — agentctl server route groups, adapter model, ACP protocol
• internal/agentctl/server/api/AGENTS.md — reverse-proxy body rewriting (Accept-Encoding), iframe-blocking header stripping
• internal/integrations/AGENTS.md — playbook for adding a new third-party integration (Jira/Linear pattern)
• cmd/mock-agent/AGENTS.md — predefined /e2e:<name> scenarios vs inline e2e:... scripts, recipe for adding a scenario, and the rebuild-before-e2e requirement