feat(core): 0.2.4 — kernel concurrent layers, verifier ecosystem, parity harness

.claude-plugin/marketplace.json

@@ -10,14 +10,14 @@
   "plugins": [
     {
       "name": "taskflow",
-      "description": "Multi-phase subagent orchestration for Codex: 16 taskflow_* MCP tools (run/runs/resume/version/list/show/verify/compile/peek/trace/replay/why_stale/recompute/reconcile_workspace/save/search) plus a routing skill. Background runs support status/wait/cancel; compile returns SVG + text outline. The server runs via npx (codex-taskflow).",
+      "description": "Multi-phase subagent orchestration for Codex: 17 taskflow_* MCP tools (run/runs/resume/version/list/show/verify/compile/lint/peek/trace/replay/why_stale/recompute/reconcile_workspace/save/search) plus a routing skill. Background runs support status/wait/cancel; compile returns SVG + text outline. The server runs via npx (codex-taskflow).",
       "source": "./packages/codex-taskflow/plugin",
       "category": "developer-tools",
       "homepage": "https://github.com/heggria/taskflow"
     },
     {
       "name": "claude-taskflow",
-      "description": "Multi-phase subagent orchestration for Claude Code: 16 taskflow_* MCP tools (run/runs/resume/version/list/show/verify/compile/peek/trace/replay/why_stale/recompute/reconcile_workspace/save/search) plus a routing skill. Background runs support status/wait/cancel; compile returns SVG + text outline. The server runs via npx (claude-taskflow).",
+      "description": "Multi-phase subagent orchestration for Claude Code: 17 taskflow_* MCP tools (run/runs/resume/version/list/show/verify/compile/lint/peek/trace/replay/why_stale/recompute/reconcile_workspace/save/search) plus a routing skill. Background runs support status/wait/cancel; compile returns SVG + text outline. The server runs via npx (claude-taskflow).",
       "source": "./packages/claude-taskflow/plugin",
       "category": "developer-tools",
       "homepage": "https://github.com/heggria/taskflow"

.grok-plugin/marketplace.json

@@ -8,7 +8,7 @@
   "plugins": [
     {
       "name": "taskflow",
-      "description": "Multi-phase subagent orchestration for Grok Build: 16 taskflow_* MCP tools (run/runs/resume/version/list/show/verify/compile/peek/trace/replay/why_stale/recompute/reconcile_workspace/save/search) plus a routing skill. Background runs support status/wait/cancel; compile returns SVG + text outline. The server runs via npx (grok-taskflow).",
+      "description": "Multi-phase subagent orchestration for Grok Build: 17 taskflow_* MCP tools (run/runs/resume/version/list/show/verify/compile/lint/peek/trace/replay/why_stale/recompute/reconcile_workspace/save/search) plus a routing skill. Background runs support status/wait/cancel; compile returns SVG + text outline. The server runs via npx (grok-taskflow).",
       "source": {
         "type": "local",
         "path": "./packages/grok-taskflow/plugin"

CHANGELOG.md

@@ -2,6 +2,29 @@
 
 All notable changes to taskflow are documented here. This project follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/) format.
 
+## [0.2.4] — 2026-07-20
+
+### Added
+
+- **Event kernel concurrent DAG layers.** The event kernel now executes phases within a topological layer concurrently via `Promise.all` with atomic layer-boundary commit. Gate and budget decisions are checked between layers, not within. This removes the single largest blocker to kernel default-ON: previously any flow with independent parallel phases (the common case) was forced to the imperative runtime.
+- **Kernel retry support.** `phase.retry = { max, backoffMs, factor }` is now honored on the event kernel path for ALL failures (not just transient errors), matching the imperative contract. Both `runOneAgent` (step.ts) and `runAgentCall` (step-kinds.ts) implement the full retry curve with budget-aware admission.
+- **Kernel context pre-read.** `phase.context` files are now read and prepended to the prompt as `<context file="...">` blocks on the event kernel path, matching the imperative runtime's `resolvePhaseContext` behavior.
+- **Kernel per-phase literal cwd.** Literal string `phase.cwd` values (absolute or relative to the flow cwd) are now resolved and passed to `runTask` on the event kernel path. Interpolation placeholder cwds (`{args.*}`, `{steps.*}`) and workspace keywords (`temp`/`dedicated`/`worktree`) remain imperative-only.
+- **Built-in script-lint verifier.** New `scriptLintVerifier` (exported from `taskflow-core/verifiers`) statically analyzes `script` phase `run` commands for common shell mistakes: `grep` patterns starting with `-` without a `--` separator, unbalanced regex brackets/parens in `grep`/`sed`, and pipelines ending with a filter (`grep`/`awk`/`head`/`tail`/`wc`/`sort`) without `set -o pipefail` or `PIPESTATUS`. Auto-included by `compileTaskflow` (opt out with `lint: false`). Motivated by issue #82.
+- **Verifier discovery.** New `discoverVerifiers(cwd)` API loads project-local verifiers from `.pi/taskflows/verifiers/` (project scope, shadows user) and `~/.pi/taskflows/verifiers/` (user scope). Each `.ts`/`.js`/`.mjs` file is dynamically imported; default, `verifier`, and `verifiers` exports are collected. Fail-open: broken modules are skipped with a warning. Convention over configuration — no config file needed.
+- **MCP `taskflow_lint` tool.** The 17th MCP tool. Runs built-in and discovered pluggable verifiers on a flow without executing it. Exposes the verifier ecosystem to all MCP hosts (Codex, Claude Code, OpenCode, Grok Build). Provide `name`, `define`, or `defineFile`.
+- **Compile subgraph visualization.** Inline flow definitions (`phase.def`) now render as Mermaid `subgraph` blocks showing child phases and their dependency edges. Saved-use flows (`phase.use`) remain plain nodes. The subgraph title shows the child flow's name.
+- **S5.0 kernel parity harness.** New `kernel-parity.test.ts`: 11 golden fixture flows run on BOTH engines (imperative + event kernel) with a deterministic mock runner, asserting status, per-phase output, error, and gate-decision parity. Covers: linear chain, concurrent independent agents, gate, reduce, when-guard skip, join-any with optional dep, script, loop, three-layer wide DAG, retry, and gate-in-concurrent-layer. This is the differential gate that must stay green before the kernel can be flipped to default ON (S5.2).
+
+### Changed
+
+- **MCP tool count is now 17.** `taskflow_lint` joins the existing 16 tools. Marketplace metadata, host adapter tool-roster tests, and skill discovery assertions are synchronized.
+- **Kernel admission expanded.** `canUseEventKernel` now admits flows with: concurrent DAG layers, explicit `retry`, `context` pre-read, and literal per-phase `cwd`. Remaining imperative-only features: `score` gates, `expect` contracts, `reflexion`, `onBlock:retry`, `reduceStrategy:"tree"`, cross-run cache, `shareContext`, per-branch cwd, script stdin input, interpolated script argv, budgeted fan-out, and budgeted loop/tournament.
+
+### Fixed
+
+- **Gate parity normalization.** The kernel parity harness normalizes gate objects to strip `reason: undefined` vs absent-key serialization differences between the two engines.
+
 ## [0.2.3] — 2026-07-18
 
 ### Added

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pi-taskflow-monorepo",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "private": true,
   "description": "Monorepo for taskflow-core, taskflow-mcp-core, taskflow-hosts, taskflow-dsl, pi-taskflow, codex-taskflow, claude-taskflow, opencode-taskflow, grok-taskflow, and the documentation website.",
   "type": "module",

packages/claude-taskflow/package.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-taskflow",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "Run taskflow on Claude Code: a Claude subagent runner plus an MCP server (and a plug-and-play Claude Code plugin) that exposes the taskflow_* tools to Claude Code users.",
   "keywords": [
     "claude",

packages/claude-taskflow/plugin/skills/taskflow/SKILL.md

@@ -148,6 +148,7 @@ For a non-trivial flow you'll iterate on, **write the definition to a file**
 // 2. verify, iterate, run — all reference the SAME file by path:
 { "name": "taskflow_verify", "arguments": { "defineFile": "/tmp/audit.json" } }  // zero tokens
 { "name": "taskflow_compile", "arguments": { "defineFile": "/tmp/audit.json" } }  // diagram
+{ "name": "taskflow_lint",   "arguments": { "defineFile": "/tmp/audit.json" } }  // script-lint + custom verifiers
 { "name": "taskflow_run",    "arguments": { "defineFile": "/tmp/audit.json" } }
 ```
 

packages/claude-taskflow/plugin/skills/taskflow/advanced.md

@@ -206,6 +206,56 @@ overrides, ordinary resume re-runs the non-done phases.
 
 ---
 
+## Pluggable verifiers — zero-token custom static checks
+
+Beyond the built-in structural detectors (dead-ends, unreachable, gate-exhaustion,
+budget-overflow, concurrency, ref-integrity, guard-contradictions, contracts),
+Taskflow supports **pluggable verifiers**: pure functions that lint a flow's
+declarations at compile time, before any model is spawned.
+
+### Built-in: script-lint
+
+`compileTaskflow` auto-includes the **script-lint** verifier (opt out with
+`lint: false`). It catches common shell mistakes in `script` phase `run`
+commands:
+
+- `grep` pattern starting with `-` without a `--` separator (exit 2, false RED)
+- Unbalanced `[` or `(` in `grep`/`sed` regex (exit 2)
+- Pipeline ending with a filter (`grep`/`awk`/`head`/`tail`/`wc`/`sort`)
+  without `set -o pipefail` or `PIPESTATUS` (failing upstream masked)
+
+### Custom verifiers (convention dir)
+
+Drop a `.ts`/`.js`/`.mjs` file in `.pi/taskflows/verifiers/` (project) or
+`~/.pi/taskflows/verifiers/` (user). Export a `TaskflowVerifier`:
+
+```ts
+export default {
+  name: "my-check",
+  verify(flow) {
+    // flow.phases, flow.budget, flow.name are available.
+    // Return VerifierIssue[]: { phaseId?, message, severity: "error"|"warning" }.
+    return [];
+  },
+};
+```
+
+Project-scope verifiers shadow user-scope by `name`. Broken modules are
+skipped with a warning (fail-open). Use `taskflow_lint` (MCP) or
+`verifyTaskflow(flow, { verifiers })` (programmatic) to run them.
+
+### MCP: `taskflow_lint`
+
+```
+taskflow_lint { "defineFile": "/tmp/flow.json" }
+```
+
+Runs built-in + discovered verifiers. Plugin issues are stamped
+`category: "plugin"` with `source: <verifier-name>`. Structural issues
+are covered by `taskflow_verify`; `taskflow_lint` reports only plugin findings.
+
+---
+
 ## `taskflow_version` — build/host identity
 
 `taskflow_version` reports the engine package version, the git commit the dist

packages/claude-taskflow/test/mcp-server.test.ts

@@ -45,15 +45,15 @@ test("claude mcp: initialize returns the protocol version + serverInfo", async (
 	assert.equal(res.result.protocolVersion, "2025-06-18");
 	assert.ok(res.result.capabilities.tools, "advertises tools capability");
 	assert.equal(res.result.serverInfo.name, "taskflow-claude");
-	assert.equal(res.result.serverInfo.version, "0.2.3");
+	assert.equal(res.result.serverInfo.version, "0.2.4");
 });
 
 test("claude mcp: tools/list exposes the same taskflow tools as codex", async () => {
 	const [res] = await rpcRoundtrip([{ jsonrpc: "2.0", id: 2, method: "tools/list", params: {} }]);
 	const names = res.result.tools.map((t: any) => t.name);
 	assert.deepEqual(
 		names.sort(),
-		["taskflow_compile", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
+		["taskflow_compile", "taskflow_lint", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
 	);
 	for (const t of res.result.tools) {
 		assert.equal(typeof t.description, "string");
@@ -83,6 +83,6 @@ test("claude mcp: makeToolHandlers exposes the tools", () => {
 	const tools = makeToolHandlers(process.cwd());
 	assert.deepEqual(
 		Object.keys(tools).sort(),
-		["taskflow_compile", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
+		["taskflow_compile", "taskflow_lint", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
 	);
 });

packages/codex-taskflow/package.json

@@ -1,6 +1,6 @@
 {
   "name": "codex-taskflow",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "Run taskflow on OpenAI Codex: a Codex subagent runner plus an MCP server (and a plug-and-play Codex plugin) that exposes the taskflow_* tools to Codex users.",
   "keywords": [
     "codex",

packages/codex-taskflow/plugin/skills/taskflow/SKILL.md

@@ -143,6 +143,7 @@ For a non-trivial flow you'll iterate on, **write the definition to a file**
 // 2. verify, iterate, run — all reference the SAME file by path:
 { "name": "taskflow_verify", "arguments": { "defineFile": "/tmp/audit.json" } }  // zero tokens
 { "name": "taskflow_compile", "arguments": { "defineFile": "/tmp/audit.json" } }  // diagram
+{ "name": "taskflow_lint",   "arguments": { "defineFile": "/tmp/audit.json" } }  // script-lint + custom verifiers
 { "name": "taskflow_run",    "arguments": { "defineFile": "/tmp/audit.json" } }
 ```
 

packages/codex-taskflow/plugin/skills/taskflow/advanced.md

@@ -206,6 +206,56 @@ overrides, ordinary resume re-runs the non-done phases.
 
 ---
 
+## Pluggable verifiers — zero-token custom static checks
+
+Beyond the built-in structural detectors (dead-ends, unreachable, gate-exhaustion,
+budget-overflow, concurrency, ref-integrity, guard-contradictions, contracts),
+Taskflow supports **pluggable verifiers**: pure functions that lint a flow's
+declarations at compile time, before any model is spawned.
+
+### Built-in: script-lint
+
+`compileTaskflow` auto-includes the **script-lint** verifier (opt out with
+`lint: false`). It catches common shell mistakes in `script` phase `run`
+commands:
+
+- `grep` pattern starting with `-` without a `--` separator (exit 2, false RED)
+- Unbalanced `[` or `(` in `grep`/`sed` regex (exit 2)
+- Pipeline ending with a filter (`grep`/`awk`/`head`/`tail`/`wc`/`sort`)
+  without `set -o pipefail` or `PIPESTATUS` (failing upstream masked)
+
+### Custom verifiers (convention dir)
+
+Drop a `.ts`/`.js`/`.mjs` file in `.pi/taskflows/verifiers/` (project) or
+`~/.pi/taskflows/verifiers/` (user). Export a `TaskflowVerifier`:
+
+```ts
+export default {
+  name: "my-check",
+  verify(flow) {
+    // flow.phases, flow.budget, flow.name are available.
+    // Return VerifierIssue[]: { phaseId?, message, severity: "error"|"warning" }.
+    return [];
+  },
+};
+```
+
+Project-scope verifiers shadow user-scope by `name`. Broken modules are
+skipped with a warning (fail-open). Use `taskflow_lint` (MCP) or
+`verifyTaskflow(flow, { verifiers })` (programmatic) to run them.
+
+### MCP: `taskflow_lint`
+
+```
+taskflow_lint { "defineFile": "/tmp/flow.json" }
+```
+
+Runs built-in + discovered verifiers. Plugin issues are stamped
+`category: "plugin"` with `source: <verifier-name>`. Structural issues
+are covered by `taskflow_verify`; `taskflow_lint` reports only plugin findings.
+
+---
+
 ## `taskflow_version` — build/host identity
 
 `taskflow_version` reports the engine package version, the git commit the dist

packages/codex-taskflow/test/e2e-mcp-comprehensive.mts

@@ -79,7 +79,7 @@ send({ jsonrpc: "2.0", id: 1, method: "initialize", params: { protocolVersion: "
 const init = await waitFor(1, "initialize");
 assert.equal(init.result.protocolVersion, "2025-06-18");
 assert.equal(init.result.serverInfo.name, "taskflow-codex");
-assert.equal(init.result.serverInfo.version, "0.2.3");
+assert.equal(init.result.serverInfo.version, "0.2.4");
 ok(`initialize → ${JSON.stringify(init.result.serverInfo)}`);
 
 // notification must NOT produce a response
@@ -88,7 +88,7 @@ send({ jsonrpc: "2.0", method: "notifications/initialized" });
 send({ jsonrpc: "2.0", id: 2, method: "tools/list", params: {} });
 const list = await waitFor(2, "tools/list");
 const toolNames = list.result.tools.map((t: any) => t.name).sort();
-assert.deepEqual(toolNames, ["taskflow_compile", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"]);
+assert.deepEqual(toolNames, ["taskflow_compile", "taskflow_lint", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"]);
 for (const t of list.result.tools) {
 	assert.equal(t.inputSchema.type, "object", `${t.name} has object schema`);
 	assert.equal(typeof t.description, "string");

packages/codex-taskflow/test/mcp-server.test.ts

@@ -51,15 +51,15 @@ test("mcp: initialize returns the protocol version + serverInfo codex expects",
 	assert.equal(res.result.protocolVersion, "2025-06-18");
 	assert.ok(res.result.capabilities.tools, "advertises tools capability");
 	assert.equal(res.result.serverInfo.name, "taskflow-codex");
-	assert.equal(res.result.serverInfo.version, "0.2.3");
+	assert.equal(res.result.serverInfo.version, "0.2.4");
 });
 
 test("mcp: tools/list exposes the taskflow tools with schemas", async () => {
 	const [res] = await rpcRoundtrip([{ jsonrpc: "2.0", id: 2, method: "tools/list", params: {} }]);
 	const names = res.result.tools.map((t: any) => t.name);
 	assert.deepEqual(
 		names.sort(),
-		["taskflow_compile", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
+		["taskflow_compile", "taskflow_lint", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
 	);
 	for (const t of res.result.tools) {
 		assert.equal(typeof t.description, "string");
@@ -245,7 +245,7 @@ test("mcp: makeToolHandlers exposes the tools", () => {
 	const tools = makeToolHandlers(process.cwd());
 	assert.deepEqual(
 		Object.keys(tools).sort(),
-		["taskflow_compile", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
+		["taskflow_compile", "taskflow_lint", "taskflow_list", "taskflow_peek", "taskflow_recompute", "taskflow_reconcile_workspace", "taskflow_replay", "taskflow_resume", "taskflow_run", "taskflow_runs", "taskflow_save", "taskflow_search", "taskflow_show", "taskflow_trace", "taskflow_verify", "taskflow_version", "taskflow_why_stale"],
 	);
 });
 

packages/grok-taskflow/package.json

@@ -1,6 +1,6 @@
 {
   "name": "grok-taskflow",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "Run taskflow on Grok Build: a Grok subagent runner plus an MCP server (and a plug-and-play Grok plugin) that exposes the taskflow_* tools to Grok Build users.",
   "keywords": [
     "grok",

packages/grok-taskflow/plugin/skills/taskflow/SKILL.md

@@ -153,6 +153,7 @@ For a non-trivial flow you'll iterate on, **write the definition to a file**
 // 2. verify, iterate, run — all reference the SAME file by path:
 { "name": "taskflow_verify", "arguments": { "defineFile": "/tmp/audit.json" } }  // zero tokens
 { "name": "taskflow_compile", "arguments": { "defineFile": "/tmp/audit.json" } }  // diagram
+{ "name": "taskflow_lint",   "arguments": { "defineFile": "/tmp/audit.json" } }  // script-lint + custom verifiers
 { "name": "taskflow_run",    "arguments": { "defineFile": "/tmp/audit.json" } }
 ```