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Rename tool to taskgraph, use op dispatch field, add research reports

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The built-in OpenCode 'task' tool spawns subagents for work delegation.
Naming our plugin 'tasks' would create confusion with two 'task' tools
that do completely different things. 'taskgraph' matches the core
library, clearly differentiates from the built-in, and describes what
the tool actually does.

The dispatch field is renamed from 'tool' to 'op' (operation) to
avoid collision with OpenCode's 'tool' terminology and match the
Rust CLI's subcommand pattern.

ADR-001 rewritten for taskgraph/op naming and Zod/TypeBox distinction.
ADR-007 added documenting the naming decision and the three 'task'
concepts (task, todowrite, taskgraph).

Research reports added:
- docs/research/opencode-task-tool-deep-dive.md
- docs/research/open-coordinator-deep-dive.md

Also: fixed SDD process link, resolved open question about 'show'
including full body, added todowrite to relationship table, clarified
Zod vs TypeBox roles, changed FileSource to async scan.
This commit is contained in:
glm-5.1
2026-04-28 11:30:20 +00:00
parent f8b7a2fc1b
commit 9342dab70c
6 changed files with 1733 additions and 46 deletions
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docs/architecture/overview.md
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@@ -5,12 +5,24 @@ last_updated: 2026-04-28
# Open Tasks: Architecture Overview
Structured task management for OpenCode agents — graph analysis, dependency insight, decomposition guidance, and workflow cost estimation. Exposes a single `tasks` tool using a registry pattern to keep the agent's visible tool count minimal.
Structured task management for OpenCode agents — graph analysis, dependency insight, decomposition guidance, and workflow cost estimation. Exposes a single `taskgraph` tool using a registry pattern to keep the agent's visible tool count minimal.
## Problem
The `taskgraph` Rust CLI provides task graph operations but requires shell invocation — agents must compose bash commands and parse plain-text output. This is error-prone, context-expensive, and gives no structural validation or rich formatting. The TypeScript core library (`@alkdev/taskgraph`) now provides all graph operations natively. This plugin wraps that library into an OpenCode tool interface so agents get first-class, structured access without leaving the conversation.
## Naming: `taskgraph` not `tasks`
OpenCode has a built-in `task` tool that spawns subagents for work delegation. Naming our plugin `tasks` (plural) would create confusion — both deal with "tasks" but have completely different purposes:
| Tool | Concept | Scope |
|------|---------|-------|
| `task` (built-in) | **Delegation** — spawn a subagent to do work | Session-scoped, ephemeral |
| `todowrite` (built-in) | **Progress tracking** — what am I working on now | Session-scoped, flat list |
| `taskgraph` (this plugin) | **Analysis** — what work exists, what depends on what, what's risky | Persistent, graph-structured |
The name `taskgraph` directly matches the core library, clearly differentiates from the built-in `task`, and describes what the tool actually does. See [ADR-007](decisions/007-naming-taskgraph.md).
## What This Plugin Is
A **read-only analysis and query layer** on top of the project's `tasks/` directory. It:
@@ -30,33 +42,35 @@ A **read-only analysis and query layer** on top of the project's `tasks/` direct
### Single-Tool Registry Pattern
Following open-memory's proven approach, the plugin exposes **one tool** (`tasks`) with internal operation dispatch:
Following open-memory's proven approach, the plugin exposes **one tool** (`taskgraph`) with internal operation dispatch:
```
tasks({tool: "help"}) → Show available operations
tasks({tool: "list"}) → List tasks in project
tasks({tool: "show", args: {id: "..."}}) → Show task details
tasks({tool: "deps", args: {id: "..."}}) → Task prerequisites
tasks({tool: "dependents", args: {id: "..."}}) → Tasks depending on a task
tasks({tool: "validate"}) → Validate all task files
tasks({tool: "topo"}) → Topological ordering
tasks({tool: "cycles"}) → Circular dependency detection
tasks({tool: "critical"}) → Critical path
tasks({tool: "parallel"}) → Parallel execution groups
tasks({tool: "bottleneck"}) → Bottleneck analysis
tasks({tool: "risk"}) → Risk path + distribution
tasks({tool: "cost"}) → Workflow cost estimate
tasks({tool: "decompose", args: {id: "..."}}) → Decomposition guidance
taskgraph({op: "help"}) → Show available operations
taskgraph({op: "list"}) → List tasks in project
taskgraph({op: "show", args: {id: "..."}}) → Show task details
taskgraph({op: "deps", args: {id: "..."}}) → Task prerequisites
taskgraph({op: "dependents", args: {id: "..."}}) → Tasks depending on a task
taskgraph({op: "validate"}) → Validate all task files
taskgraph({op: "topo"}) → Topological ordering
taskgraph({op: "cycles"}) → Circular dependency detection
taskgraph({op: "critical"}) → Critical path
taskgraph({op: "parallel"}) → Parallel execution groups
taskgraph({op: "bottleneck"}) → Bottleneck analysis
taskgraph({op: "risk"}) → Risk path + distribution
taskgraph({op: "cost"}) → Workflow cost estimate
taskgraph({op: "decompose", args: {id: "..."}}) → Decomposition guidance
```
**Why**: Each tool definition adds JSON schema to the system prompt (~200-300 tokens each). 14 operations as 14 separate tools = ~3500 tokens of tool definitions. The registry pattern collapses this to ~250 tokens (one tool schema) plus an on-demand help text the agent retrieves only when needed. This is the same math that drove open-memory's design.
**Why `op` instead of `tool`**: The dispatch field is named `op` (operation) rather than `tool` to avoid collision with OpenCode's own "tool" terminology. An agent calling `taskgraph({tool: "list"})` reads ambiguously — is "list" a tool or an operation on the taskgraph tool? `taskgraph({op: "list"})` is clearer: "run the list operation on the taskgraph."
### Component Structure
```
src/
├── index.ts # Plugin entry: tool registration + config loading
├── tools.ts # Tool definition — single `tasks` tool with registry dispatch
├── tools.ts # Tool definition — single `taskgraph` tool with registry dispatch
├── registry.ts # Operation registry (dispatch table, arg validation)
├── config.ts # Plugin config schema + resolution (TypeBox, validated)
├── sources/
@@ -206,7 +220,7 @@ class FileSource implements TaskSource {
}
const glob = new Bun.Glob("**/*.md")
const files = Array.from(glob.scanSync({ cwd: this.dirPath }))
const files = await Array.fromAsync(glob.scan({ cwd: this.dirPath }))
// ... read each file, parse with parseFrontmatter, collect results
}
}
@@ -265,15 +279,15 @@ function createSource(config: Config, workspaceDir: string): TaskSource {
### Help Operation
`tasks({tool: "help"})` returns the full operation reference table. `tasks({tool: "help", args: {tool: "list"}})` returns detailed usage for one operation including argument shapes and example calls.
`taskgraph({op: "help"})` returns the full operation reference table. `taskgraph({op: "help", args: {op: "list"}})` returns detailed usage for one operation including argument shapes and example calls.
## Design Decisions
### D1: Registry Pattern (single tool, not 14)
- **Context**: 14 operations could each be a separate tool or collapsed into one router.
- **Choice**: Single `tasks` tool with `{tool, args}` dispatch.
- **Consequences**: Agent always has access to the help reference. Adding operations never increases context bloat. Trade-off: the `tool` and `args` fields are not individually validated by the outer schema — validation happens inside the dispatch.
- **Choice**: Single `taskgraph` tool with `{op, args}` dispatch.
- **Consequences**: Agent always has access to the help reference. Adding operations never increases context bloat. Trade-off: the `op` and `args` fields are not individually validated by the outer schema — validation happens inside the dispatch.
- **Reference**: See [ADR-001](decisions/001-registry-pattern.md)
### D2: No Caching, Fresh Graph Per Call
@@ -299,7 +313,7 @@ function createSource(config: Config, workspaceDir: string): TaskSource {
### D5: `cost` Defaults Match SDD Process
- **Context**: `workflowCost()` supports `propagationMode` (independent vs dag-propagate), `defaultQualityRetention`, and `includeCompleted`. Different defaults make sense for different workflows.
- **Choice**: Default to `propagationMode: "dag-propagate"`, `includeCompleted: false`, `defaultQualityRetention: 0.9` — matching the Spec-Driven Development (SDD) process's assumption that completed tasks are factored out of remaining cost, and that quality degrades probabilistically across dependencies. See [SDD Process](../../sdd_process.md) for the overall workflow.
- **Choice**: Default to `propagationMode: "dag-propagate"`, `includeCompleted: false`, `defaultQualityRetention: 0.9` — matching the Spec-Driven Development (SDD) process's assumption that completed tasks are factored out of remaining cost, and that quality degrades probabilistically across dependencies. See [SDD Process](../sdd_process.md) for the overall workflow.
- **Consequences**: The most common use case (active project planning) gets sensible defaults. Agents can override per-call.
### D6: Separate `registry.ts` From `tools.ts`
@@ -363,7 +377,9 @@ No hooks in v1. Future: task status injection into system prompt (similar to ope
### Tool Definition (`src/tools.ts`)
Single tool with `{tool: string, args?: Record<string, unknown>}` schema. The `tool` field dispatches to an operation handler via the registry. Unknown tool names produce a friendly error directing to `tasks({tool: "help"})`.
Single tool with `{op: string, args?: Record<string, unknown>}` schema. The `op` field dispatches to an operation handler via the registry. Unknown operation names produce a friendly error directing to `taskgraph({op: "help"})`.
The tool's parameter schema uses **Zod** (from `@opencode-ai/plugin`'s `tool()` helper) because that's what OpenCode's plugin SDK provides for tool definitions. The plugin's internal config schema uses **TypeBox** for compile-time types and runtime `Value.Check()`. These are two different concerns: Zod for the tool's external interface (what the LLM sees), TypeBox for our own config (what we validate at startup).
The `source` is passed from the plugin entry to `createTools()` and stored in the registry for all operations to use.
@@ -415,7 +431,7 @@ Operations encounter two categories of errors:
### Graph Errors (validation / cycles)
- **Cycle detection**: The `cycles` operation surfaces all cycles. Operations that require topological ordering (topo, critical, parallel, cost) catch `CircularDependencyError` and return a message suggesting `tasks({tool: "cycles"})` first
- **Cycle detection**: The `cycles` operation surfaces all cycles. Operations that require topological ordering (topo, critical, parallel, cost) catch `CircularDependencyError` and return a message suggesting `taskgraph({op: "cycles"})` first
- **Validation errors**: The `validate` operation returns both schema errors (field-level: invalid enums, missing required fields) and graph errors (dangling references, duplicate edges). Other operations call `graph.validate()` only when structural correctness matters
- **Task not found**: Operations that take a task `id` return a clear "not found" message listing the available task IDs (up to 20)
@@ -479,24 +495,32 @@ New operations can be added freely — the registry pattern means no schema bloa
| Plugin | Relationship |
|--------|-------------|
| **open-memory** | Complementary — memory handles session introspection; tasks handles task graph analysis. Both use the registry pattern. |
| **open-coordinator** | Downstream consumer — coordinator uses `tasks` to identify parallelizable work, then spawns worktrees. The `parallel` and `critical` operations inform coordination decisions. |
| **open-memory** | Complementary — memory handles session introspection; taskgraph handles task graph analysis. Both use the registry pattern. |
| **open-coordinator** | Future integration — coordinator's `spawn`/`swarm` could consume taskgraph's `parallel` and `critical` analysis for dependency-aware parallel execution. Currently no integration exists. |
| **taskgraph CLI** | Functional equivalent — the Rust CLI and this plugin expose the same operations, but this plugin is native TypeScript + in-process, while the CLI is a separate binary. |
| **@alkdev/taskgraph** | Core dependency — all graph operations. This plugin is a thin wrapper. |
| **`task` (built-in)** | Distinct concept — spawns subagents for work delegation. `taskgraph` analyzes dependencies. Future: `task` could consume `taskgraph` analysis for smarter delegation, but these are complementary, not competing. See [ADR-007](decisions/007-naming-taskgraph.md). |
| **`todowrite` (built-in)** | Complementary — session-scoped flat progress tracking. `taskgraph` operates on persistent graph-structured project files; `todowrite` tracks in-session ephemeral progress. No overlap. |
## Open Questions
1. **Should `show` include the task's markdown body?** Task files can be long (especially with acceptance criteria and notes). Option A: always include full body. Option B: `show` returns frontmatter summary, `show --full` includes body. Recommendation: always include body — agents need the full context for implementation tasks, and `show` is on-demand (not in every call).
1. ~~**Should `show` include the task's markdown body?**~~ **Resolved**: Yes. The `FileSource` provides `rawFiles` in `SourceResult`, and the `show` operation returns the full markdown body. This decision is locked in by the TaskSource design (ADR-005).
2. **Should `cost` accept `--format json`?** The CLI supports JSON output for programmatic consumption. Since the plugin returns to an agent (not a script), markdown is always appropriate. JSON output is out of scope.
3. **Future hook: task status injection?** Open-memory injects context percentage into the system prompt. Could open-tasks inject a brief task summary ("3 pending, 1 in-progress, 2 blocked")? This would require reading tasks on every message, which is cheap for small task sets but could be noisy. Defer to v2.
4. **Future: taskgraph-aware execution?** Open-coordinator's `swarm`/`spawn` operations take arrays of task names but have no dependency awareness. A natural integration would let `taskgraph({op: "parallel"})` feed directly into coordinator's `swarm` — each parallel group becomes a wave of worktrees. Similarly, the built-in `task` tool's prompt could be enriched with dependency context from `taskgraph`. Both are v2+ concerns.
5. **Should `TaskSource.load()` throw or capture errors in `SourceResult.errors`?** Per-file errors (malformed YAML, invalid schema) are captured in `errors`. Infrastructure errors (permission denied on the directory, disk failure) are thrown. This distinction needs to be documented in the `TaskSource` interface contract.
## References
- `@alkdev/taskgraph` API surface: see [`@alkdev/taskgraph` docs/architecture/api-surface.md](https://git.alk.dev/alkdev/taskgraph_ts) or the local clone at `/workspace/@alkdev/taskgraph_ts/docs/architecture/api-surface.md`
- `@alkdev/taskgraph` README: local clone at `/workspace/@alkdev/taskgraph_ts/README.md`
- open-memory architecture: `/workspace/@alkdev/open-memory/docs/architecture.md` (reference implementation for the registry pattern)
- open-memory tools.ts: `/workspace/@alkdev/open-memory/src/tools.ts` (reference for handler pattern)
- OpenCode `task` tool research: [../research/opencode-task-tool-deep-dive.md](../research/opencode-task-tool-deep-dive.md)
- open-coordinator research: [../research/open-coordinator-deep-dive.md](../research/open-coordinator-deep-dive.md)
- SDD process: [../sdd_process.md](../sdd_process.md)
- OpenCode plugin SDK: `@opencode-ai/plugin` npm package