Editor destructively reformats YAML on file open (no user action)

[intel352]

Summary

Opening a workflow YAML file in the editor (without making any changes or saving) causes the file to be silently and destructively modified on disk. The modifications include comment removal, quote style changes, array format changes, key reordering, config block deletion, and injection of new blocks.

Reproduction

Input file (service.yaml) before opening in editor:

name: my-service
version: "1.0"

# Validation settings for template references
engine:
  validation:
    templateRefs: warn

modules:
  - name: web-server
    type: http.server
    dependsOn: [web-router]
    config:
      address: ":8080"
      readTimeout: "30s"
      writeTimeout: "30s"

  - name: web-router
    type: http.router
    config:
      cors:
        allowedOrigins: ["${CORS_ORIGINS:-http://localhost:3000}"]
        allowedMethods: ["GET", "POST", "PUT", "DELETE", "OPTIONS"]
        allowedHeaders:
          - "Authorization"
          - "Content-Type"

  - name: auth
    type: auth.m2m
    config:
      clients:
        - clientId: "${CLIENT_ID}"
          clientSecret: "${CLIENT_SECRET}"
          scopes: [admin, read, write]
          description: "Primary API client"
      # Allow cross-token introspection for external services
      introspect:
        allowOthers: true

  - name: authz
    type: authz.casbin
    config:
      roleAssignments:
        - ["${CLIENT_ID}", "api_client"]
      policies:
        - ["api_client", "/v1/resources", "*"]
        - ["api_client", "/v1/resources/*", "*"]

# Health check pipeline
pipelines:
  health:
    trigger:
      type: http
      method: GET
      path: /healthz
    steps:
      - name: respond
        type: step.json_response
        config:
          status: 200
          body:
            status: ok
            time: "{{now \"RFC3339\"}}"

After simply opening the file in the editor (no user edits, no save):

version: "1.0"
name: my-service
modules:
  - name: web-server
    type: http.server
    config:
      address: ':8080'
      readTimeout: 30s
      writeTimeout: 30s
    dependsOn:
      - web-router
  - name: web-router
    type: http.router
    config:
      cors:
        allowedOrigins:
          - ${CORS_ORIGINS:-http://localhost:3000}
        allowedMethods:
          - GET
          - POST
          - PUT
          - DELETE
          - OPTIONS
        allowedHeaders:
          - Authorization
          - Content-Type
  - name: auth
    type: auth.m2m
    config:
      clients:
        - clientId: ${CLIENT_ID}
          clientSecret: ${CLIENT_SECRET}
          scopes:
            - admin
            - read
            - write
          description: Primary API client
      introspect:
        allowOthers: true
  - name: authz
    type: authz.casbin
    config:
      roleAssignments:
        - - ${CLIENT_ID}
          - api_client
      policies:
        - - api_client
          - /v1/resources
          - '*'
        - - api_client
          - /v1/resources/*
          - '*'
triggers: {}
pipelines:
  health:
    trigger:
      type: http
      method: GET
      path: /healthz
    steps:
      - name: respond
        type: step.json_response
        config:
          status: 200
          body:
            status: ok
            time: '{{now "RFC3339"}}'

Changes made silently on open (7 categories)

#	Category	Example	Impact
1	Comments deleted	All # comments removed	Loss of documentation and intent
2	Config blocks deleted	engine: block removed entirely	Functional breakage — validation settings lost
3	Quote style changed	"30s" → 30s, ":8080" → ':8080'	Inconsistent with author intent; mixed single/double/unquoted
4	Inline arrays exploded	[admin, read, write] → 3-line block	File grows significantly; harder to scan
5	Tuple arrays exploded	["client", "/path", "*"] → nested block	Casbin policies become unreadable; triples line count
6	Keys reordered	name moved after version; dependsOn moved to end of module	Breaks author's intentional logical grouping
7	Blocks injected	triggers: {} added between workflows and pipelines	Adds config that wasn't present in the original

Functional impact

Item #2 is the most critical — the engine: top-level block is silently deleted. This contains runtime configuration (engine.validation.templateRefs: warn) that affects engine behavior. The editor appears to drop any top-level keys it doesn't recognize, which means opening a file in the editor can break a working deployment.

Expected behavior

1. Opening a file should NEVER modify it unless the user explicitly requests formatting or saves
2. If reformatting is offered, it should be opt-in (e.g., a "Format Document" command), not automatic on load
3. Comments must be preserved — they are valid YAML and carry semantic meaning
4. Unknown/unrecognized top-level config blocks (like engine:) must be preserved as passthrough, not deleted
5. Quote style, array format, and key ordering should be preserved (round-trip fidelity)

Environment

• IDE: VS Code with workflow-editor extension
• OS: macOS