BPMN Generator Skill v2.0 — Enterprise Edition

Converts natural language process descriptions into OMG BPMN 2.0.2 compliant XML files and SVG previews via a 4-phase pipeline. All visual rendering follows the bpmn-js reference implementation.

Pipeline Overview

User Text
   ↓  [Phase 1] Intent Extraction  (Claude LLM)
JSON Logic-Core
   ↓  [Phase 2] Validation          (rules + deadlock detection + structural soundness)
Validated JSON
   ↓  [Phase 3] Auto-Layout         (ElkJS Sugiyama layered algorithm)
JSON + Coordinates (edge endpoints clipped to shape boundaries)
   ↓  [Phase 4] Serialization       (pipeline.js)
BPMN 2.0 XML + SVG

The LLM never handles coordinates. Layout is 100% algorithmic.

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Modes: Document (IST) vs. Optimize (Soll)

Two distinct intents — keep them separate:

• Document mode (default, IST / as-is): the user describes a process and wants it captured faithfully as BPMN. No judgment, no improvement suggestions. This is the default for every entry point (CLI, runPipeline, HTTP, MCP).
• Optimize mode (Soll / to-be): the user wants a better process. Enables the opt-in Optimization Advisory layer, which flags graph-detectable redesign opportunities (Reijers 2005 heuristics + BABOK Lean metrics) as non-blocking advisories — never auto-applied.

Select the mode consistently across entry points:

• CLI: node bpmn/pipeline.js in.json out --optimize
• Programmatic: runPipeline(lc, { mode: 'optimize' })
• HTTP: { "logicCore": {...}, "mode": "optimize" } on /api/v1/generate|validate|orchestrate
• MCP: mode: "optimize" on generate_bpmn / validate_bpmn / orchestrate_bpmn

Advisories are review suggestions with trade-off tags (time/cost/quality/flexibility); they are heuristics, not proofs — present them as options, never silently apply them. Each advisory is an object { id, transform, targets, message, tradeoff, ref, judgment } (see references/api-reference.md); message is the human-readable line, transform names the matching intervention in the toolbox below.

Redesign Toolbox

In optimize mode, an advisory's transform field names a concrete, mechanical intervention. The interventions live in scripts/bpmn/redesign.js; each has a preview* function (what would be feasible, and why not) and an apply* function that performs it:

• parallelize — puts a linear, same-lane task chain into a parallel-gateway split/join. Tasks only: a chain containing a subprocess, a call activity, an intermediate event or a gateway is refused, because parallelising a scope or a branch changes the process logic rather than the order of its steps. This is also why O04 never nominates a subprocess chain — the detector (optimize.js) is scoped to the same leaf-task set as the transform, so it cannot advise something the toolbox is guaranteed to refuse. If you want such a chain parallelised, that starts with a decision about the transform, not with the advisory
• mergeTasks — folds a linear task chain into one task; requires an explicit name — naming the result is a judgment call the toolbox refuses to make for you
• relane — moves one node to a different lane
• reorderKnockouts — reorders a chain of exclusive-gateway "knock-out" checks; requires an explicit order — it is never computed
• isolateException — turns an inline exception branch into a boundary event on the owning task; requires explicit marker and cancelActivity, and, when the exception end has more than one incoming edge, an explicit edgeIds naming which ones belong to this task — it refuses rather than guess

No-language-model guarantee: the toolbox is purely deterministic. scripts/bpmn/redesign-core.js may not import agents/llm-provider.js, directly or transitively — no LLM call, no API key. Verify with grep -rn "^import.*llm-provider" scripts/redesign*.js (no hit; a plain grep -rn "llm-provider" also matches the comment stating this rule, so it is not a useful check on its own).

Rollback: every apply* re-checks its result against a fixed, profile-independent soundness gate (soundness + workflow-net layers, always on — scripts/bpmn/redesign-core.js: SOUNDNESS_GATE) and rolls back (throws, writes nothing) on structural errors. Style warnings never block; they come back in the result's warnings array instead.

What it will not decide for you: the toolbox never decides whether an intervention should happen — that's the caller's call. Where a transform lacks the information to act safely (no proven data-independence between two tasks, no supplied ordering, no supplied marker/cancelActivity, an ambiguous set of incoming edges) it refuses with a specific reason instead of guessing. Not every transform currently has a matching automatic advisory either: O01→isolateException, O02→reorderKnockouts, O03→relane, O04→parallelize are detected by optimize.js; mergeTasks has no detector and is reachable only by direct/manual invocation.

Protection lists (policy.protectNodes / policy.protectLanes) match a node or lane by id and by display name, and resolve lane membership whether the model expresses it via node.lane or via Lane.nodeIds. Transforms also maintain both representations: a transform that deletes a node removes it from any Lane.nodeIds, and one that creates a node adds it — so the two never contradict each other. Purely Format-A models are left untouched (no nodeIds arrays are introduced).

Every apply* returns a change record with three arrays — added, removed, modified — that together name every element (node, edge, or lane) that differs between input and result.

CLI (preview is the default; nothing is written without --apply; a refusal exits non-zero and writes nothing):

node bpmn/redesign-cli.js <input.json> <parallelize|mergeTasks|relane|reorderKnockouts|isolateException> \
  [--nodes a,b,c] [--name "..."] [--lane X] [--order g2,g1] [--end xend] [--attach-to task] \
  [--marker timer] [--cancel-activity true|false] [--edges j2,j5] [--policy '{"protectNodes":[...]}'] \
  [--apply] [-o out.json]

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Reference Files

Read these when needed:

• references/logic-core-schema.md — Full JSON schema, type table, all examples → read before extracting JSON
• references/prompt-template.md — LLM prompt templates for extraction, review, amendment → read before prompting

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Supported BPMN 2.0 Elements

Events

Type	Markers	Notes
Start Event	None, Message, Timer, Signal, Conditional, Error, Escalation, Compensation	Thin circle (strokeWidth 2)
End Event	None, Message, Signal, Error, Escalation, Compensation, Cancel, Terminate, Multiple	Thick circle (strokeWidth 4)
Intermediate Catch	Message, Timer, Signal, Conditional, Link, Error, Escalation, Compensation, Cancel	Double circle
Intermediate Throw	Message, Signal, Link, Escalation, Compensation	Double circle, filled marker
Boundary Event	Timer, Error, Message, Signal, Escalation, Compensation, Cancel, Conditional	Attached to activity, interrupting/non-interrupting

Activities

Type	Icon	Notes
Task	—	Generic activity
User Task	👤	Human work item
Service Task	⚙⚙	System/API call
Script Task	📄	Script execution
Send Task	✉ (filled)	Outgoing message
Receive Task	✉ (outlined)	Incoming message
Manual Task	✋	Physical work
Business Rule Task	📊	DMN / rule engine
Sub-Process	[+]	Collapsed, with expand marker
Call Activity	thick border	Reusable called process

Activity Markers (bottom-center)

Marker	Property	Visual
Standard Loop	loopType: "standard"	↻ circular arrow
MI Parallel	multiInstance: "parallel"	⫴ three vertical bars
MI Sequential	multiInstance: "sequential"	≡ three horizontal bars
Ad-Hoc	isAdHoc: true	~ tilde
Compensation	isCompensation: true	◁◁ double rewind

Gateways

Type	Marker	Direction
Exclusive (XOR)	✕	Diverging/Converging/Mixed
Parallel (AND)	+	Diverging/Converging/Mixed
Inclusive (OR)	○	Diverging/Converging/Mixed
Event-Based	○+⬠	Diverging
Complex	✱	Mixed

Data & Artifacts

Type	Visual
Data Object	Rectangle with folded corner
Data Store	Cylinder
Text Annotation	Open bracket [ with text
Group	Dashed rounded rectangle

Connections

Type	Style	Source marker	Target marker
Sequence Flow	Solid	—	Filled triangle
Default Flow	Solid	Diagonal slash	Filled triangle
Conditional Flow	Solid	Open diamond	Filled triangle
Message Flow	Dashed (10,12)	Open circle	Open triangle
Association	Dotted (0.5,5)	—	Open chevron (if directed)

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When to use which mode

Context	Mode
User gives a process description in text	Full pipeline (all 4 phases)
User uploads/provides existing Logic-Core JSON	Skip Phase 1, start at Phase 2
User wants to add/change something in existing diagram	Amendment flow
User describes multiple organizations interacting	Multi-pool mode
User is in Claude Code with Node.js	Use scripts/bpmn/pipeline.js
User is in Claude.ai (no script execution)	Inline mode: generate XML + SVG as artifacts

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Phase 1 — Intent Extraction

Read references/logic-core-schema.md and references/prompt-template.md first.

Use the Master Extraction Prompt template. Key rules to enforce:

Naming Conventions (BA-Quality)

• Tasks: Objekt + Verb (Infinitiv) — "Antrag prüfen" ✓ / "Prüfung" ✗
• XOR Gateways: Question form — "Antrag gültig?" ✓ / "Entscheidung" ✗
• AND/OR Gateways: Empty or brief label — "" ✓ (these are sync points)
• Gateway edges: Always labeled — "Ja"/"Nein", "genehmigt"/"abgelehnt"
• Lanes: Functional roles — "Sachbearbeiter" ✓ / "Max Müller" ✗
• Events: Noun phrase — "Antrag eingegangen" ✓

Granularity Rules

• Max 7–10 nodes per level. Use subProcess for groups with >3 logical steps.
• Never create "God-Tasks" (a single task hiding a whole sub-process).
• Prefer more granular over too abstract.

Happy Path

• Mark the main success flow edges with "isHappyPath": true
• ElkJS will lay these out on the horizontal axis (left→right)
• Exception/error paths branch vertically

Gateway Direction (OMG spec §10.5.1)

• has_join: true → pipeline sets gatewayDirection="Converging" in XML
• Split gateways get gatewayDirection="Diverging" automatically
• Mixed (split+join) gateways get gatewayDirection="Mixed"

Event Markers

• Set marker explicitly when the event type is clear from context
• If not set, pipeline infers from event name (e.g. "Frist abgelaufen" → timer)

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Phase 2 — Validation

The pipeline validates automatically. These checks run:

Errors (block pipeline):

• At least one startEvent exists per process
• At least one endEvent exists per process
• All edge.source and edge.target reference existing node IDs
• No XOR-split path merging at an AND-join (deadlock detection)
• Message flows reference valid node/pool IDs

Warnings (report but continue):

• XOR gateways not named as questions
• Tasks not following Objekt + Verb (Infinitiv) pattern (M01)
• Nodes with no edges (isolated)
• XOR gateway outgoing edges without labels
• Nodes with no outgoing flow (may not terminate)

Use the Reviewer Agent Prompt from references/prompt-template.md for additional automated review.

Pre-Delivery Gate (MANDATORY — do not skip)

A first draft is expected to be wrong. Never present a diagram as finished until it passes this gate. Warnings are not noise — they are the alarm.

1. Read references/logic-core-schema.md first. It is the field-by-field contract (every node type, marker, edge, message flow, black-box pool). Fill the input file against it — do not guess field names or values.
2. Validate the draft against the schema and run it strictly:

   node bpmn/pipeline.js <input>.json <output> --strict
   

   • The schema-gate (references/input-schema.json) rejects malformed structure with a precise field path and exits non-zero — fix every reported field.
   • --strict makes every warning fatal (exit non-zero, no files written), across three independent checks: rule-engine warnings, diagram (DI) integrity, and BPMN serialisation (the round trip of the generated XML through bpmn-moddle — this is what catches an invalid element, e.g. an annotation carrying an illegal attribute).
3. Resolve every warning and re-run until --strict exits 0. Delivering a diagram with unresolved warnings is not allowed.
4. Only then present the output. If a warning is a deliberate, justified exception, say so explicitly to the user — do not silently ship past it.

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Phase 3 + 4 — Script Execution (Claude Code)

Setup (first time only)

cd scripts/
npm install   # installs runtime + dev dependencies (see package.json)

Run pipeline

# From JSON file:
node bpmn/pipeline.js my-process.json my-process

# From stdin (inline JSON):
echo '{ ... }' | node bpmn/pipeline.js - output

# Outputs:
#   output.bpmn  — BPMN 2.0 XML with full DI coordinates
#   output.svg   — SVG preview (open in browser)

OMG Compliance Guarantees

The generated BPMN 2.0 XML ensures:

• Single <laneSet> per process (spec §10.5)
• Correct gatewayDirection attribute (Diverging/Converging/Mixed)
• conditionExpression as child element, not attribute (spec §10.3.1)
• <incoming> and <outgoing> references on all flow nodes
• Event definition child elements (messageEventDefinition, timerEventDefinition, etc.)
• Loop/multi-instance characteristics as child elements
• Boundary events with attachedToRef and cancelActivity
• Valid isHorizontal="true" on pool/lane shapes
• Edge endpoints clipped to actual shape boundaries

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Inline Mode (Claude.ai — no script execution)

When Claude Code is not available, generate outputs directly in the conversation:

1. Extract the Logic-Core JSON (show to user for confirmation)
2. Apply validation rules mentally (check for deadlocks, naming, completeness)
3. For the SVG: render as an HTML artifact using inline SVG
   • Use the exact OMG dimensions: 36px events, 100×80 tasks, 50×50 gateways
   • Use ElkJS-compatible manual positioning: elements spaced 60px between layers, 40px between nodes
   • Apply stroke widths: 2 (start), 4 (end), 1.5 (intermediate), 2 (task), 5 (call activity)
4. For the BPMN XML: generate as a code artifact following all OMG compliance rules

Show the Logic-Core JSON to the user before generating final files.

Note: Inline mode coordinates are manually estimated. For production-quality layout, use Claude Code with the pipeline script.

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Amendment Flow (editing existing diagrams)

When user wants to modify an existing diagram:

1. Load the existing Logic-Core JSON
2. Use the Amendment Prompt from references/prompt-template.md
3. Apply only the atomic changes requested
4. Re-validate (Phase 2)
5. Re-run pipeline (Phase 3+4)

Never regenerate the entire Logic-Core from scratch for small edits — preserve all existing IDs.

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Two-Agent Pattern (production quality)

For enterprise output, run Modeler + Reviewer in loop:

Modeler (Claude):  Text → Logic-Core JSON (draft)
     ↓
Reviewer (Claude): Logic-Core → Issues JSON
     ↓
  No issues? → Run pipeline
  Issues?    → Modeler applies fixes → repeat (max 3 iterations)

Use prompts from references/prompt-template.md for both roles.

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Output Artifacts

File	Purpose	Opens in
*.bpmn	BPMN 2.0 XML with DI	Camunda Modeler, bpmn.io, ADONIS, Signavio
*.svg	Vector preview	Browser, Confluence, Word/PowerPoint
*_logic.json	Logic-Core (save for amendments)	Text editor, version control

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Error Handling

Error	Cause	Fix
Missing startEvent	No start node in JSON	Add startEvent node
Missing endEvent	No end node in JSON	Add endEvent node
Unknown source/target	Edge references non-existent node	Fix ID typo
Deadlock: XOR-split feeds AND-join	Structural error	Change AND-join to XOR-join or restructure
ELK layout failed	Disconnected graph	Fix isolated nodes
npm install fails	No network or Node.js missing	Ensure Node.js ≥20

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Quick-Reference: Node Types

Type	Icon	Use for
startEvent	○	Process trigger
endEvent	⬤	Process end
intermediateCatchEvent	◎	Wait for event mid-flow
intermediateThrowEvent	◎●	Send event mid-flow
boundaryEvent	◎→	Timer/error on task
userTask	👤	Human work item
serviceTask	⚙	System/API call
scriptTask	📄	Script execution
sendTask	✉●	Send message
receiveTask	✉○	Receive message
businessRuleTask	📊	DMN / rules
manualTask	✋	Physical work
subProcess	[+]	Collapsed complexity
callActivity	▬▬	Reusable process
exclusiveGateway	◇✕	One path (XOR)
parallelGateway	◇+	All paths (AND)
inclusiveGateway	◇○	One or more (OR)
eventBasedGateway	◇◎	First event wins
complexGateway	◇✱	Custom logic
dataObjectReference	📋	Document/data
dataStoreReference	🗄	Database
textAnnotation	[	Explanatory note

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Round-Tripping (BPMN Import)

Import existing BPMN 2.0 XML files to extract a Logic-Core JSON for editing.

Claude Code

cd scripts/
node bpmn/import.js existing-diagram.bpmn extracted.json

Workflow

Existing .bpmn file
   ↓  [import.js] Parse XML → extract nodes, edges, lanes, message flows
Logic-Core JSON
   ↓  [User/LLM edits]  Amendment flow
Modified Logic-Core
   ↓  [pipeline.js]  Layout + render
New .bpmn + .svg

Supported on import: Processes, collaborations, lanes, message flows, collapsed pools, gateways (with direction), all task/event types, boundary events, loop/MI markers, data objects, associations, process documentation, default flows.

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Inline Mode (Claude.ai — with ElkJS)

When Claude Code is not available, use the inline template from references/inline-template.md to create a self-contained HTML artifact:

1. Extract the Logic-Core JSON
2. Show to user for confirmation
3. Create an HTML artifact with the template
4. Replace __LOGIC_CORE_JSON__ with the actual JSON

The template runs ElkJS from CDN in the browser — no manual coordinate estimation. It produces orthogonal layouts with proper BPMN shapes.

Note: The inline renderer is simplified (no task type icons, no event markers). For full rendering fidelity, use Claude Code with pipeline.js.

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Collapsed Pools (Black-Box Participants)

Best Practice (Bruce Silver Method & Style): A diagram should have one expanded pool (your process in scope) and collapsed pools for external participants (customers, suppliers, authorities).

Schema

{
  "collapsedPools": [
    { "id": "Pool_Kunde", "name": "Versicherungsnehmer" },
    { "id": "Pool_Gutachter", "name": "Externer Gutachter" }
  ]
}

Rendering

• SVG: Thin horizontal band (600×60) with centered label
• XML: <participant> without processRef (OMG spec §9.3)
• Message flows target the collapsed pool ID directly

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Associations (Data Objects + Annotations)

Connect Data Objects, Data Stores, and Text Annotations to flow nodes:

{
  "associations": [
    { "id": "assoc1", "source": "task_erfassen", "target": "do_akte", "directed": true },
    { "id": "assoc2", "source": "ann_hinweis", "target": "task_pruefen" }
  ]
}

• SVG: Dotted line (strokeDasharray 0.5,5)
• XML: <association> element with associationDirection, placed in <artifacts> alongside any TextAnnotation/Group it connects to — never in <flowElements> (§10.7). Endpoint resolution has to look in both collections: an association's source or target is very often an artifact, not a flow node.

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OMG Compliance Checklist (v3)

Feature	Status	OMG Reference
Single <laneSet> per process	✅	§10.5
gatewayDirection Diverging/Converging/Mixed	✅	§10.5.1
default attribute on XOR gateways	✅	§10.5.1
conditionExpression as child element	✅	§10.3.1
<incoming>/<outgoing> on flow nodes	✅	§10.2.1
Top-level <message>/<signal>/<error> definitions	✅	§8.4, §9
Event definitions with messageRef/errorRef	✅	§10.4
<documentation> on process and nodes	✅	§8.3.1
<association> elements	✅	§7.2
Artifacts (TextAnnotation, Group, Association) in <artifacts>, never <flowElements>	✅	§10.7
TextAnnotation content as a <text> child element, never a name attribute	✅	§10.7.3
Group label via categoryValueRef → a Category/CategoryValue root element, never a name attribute	✅	§10.7.2
Collapsed pool (<participant> without processRef)	✅	§9.3
DI Label Bounds with <dc:Bounds>	✅	§12.1
Loop/MI characteristics as child elements	✅	§10.2.2
Boundary events with attachedToRef	✅	§10.4.4
Orthogonal edge routing	✅	Visual convention
Edge endpoint clipping to shape boundaries	✅	Visual convention
Pool width equalization	✅	Visual convention
Deadlock detection (XOR→AND)	✅	Structural soundness
Round-tripping (BPMN→JSON→BPMN)	✅	Interoperability

Why the three artifact rules above matter if you ever hand-write XML (inline mode): an Artifact (TextAnnotation, Group, Association) extends BaseElement, which declares only id — name is introduced further down by FlowElement, and Artifacts never inherit from it. Most XML libraries write the attribute anyway without complaint, so a name on a TextAnnotation produces no error and an empty box in every real BPMN tool. This shipped once; see references/omg-compliance.md §10.7 for the full mapping.