In summary, {{ year }}, {{ month }}, {{ day }} tags are empty, whereas in the slug, they are the actual year, month, and date, even though summary is supposed to have the same template tags as slug

[alberto56]

Describe the bug

Documentation states that the "summary" setting has:

Template tags are the same as those for slug

I would therefore expect the following to be possible:

collections:
  - name: 'articles'
    create: true
    label: 'Articles'
    folder: 'docs/_articles/_posts/'
    slug: '{{year}}-{{month}}-{{day}}-{{slug}}'
    summary: '{{year}}-{{month}}-{{day}} - {{title}}'
    fields:
      - label: 'Title'
        name: 'title'

If on March 16, 2026, I create a new article with the title "test", the resulting filename is, as expected:

./docs/_articles/_posts/2026-03-16-test.md

Because "summary" has the same tags as "slug", I would expect the title to be:

2026-03-16 test

However in reality it is

-- - test

So my articles look like this:

To Reproduce

Step 1: In your config.yml add:

collections:
  - name: 'articles'
    create: true
    label: 'Articles'
    folder: 'docs/_articles/_posts/'
    slug: '{{year}}-{{month}}-{{day}}-{{slug}}'
    summary: '{{year}}-{{month}}-{{day}} - {{title}}'
    fields:
      - label: 'Title'
        name: 'title'

Step 2: create an article "test"

Step 3: go to the article listing

Step 4: observe that the article is "-- - test", not "2026-03-16 - test" (but with the actual date you used).

Expected behavior

Either at step 4 above, we will see "2026-03-16 - test", or, in https://decapcms.org/docs/configuration-options/, under "summary", the sentence "Template tags are the same as those for slug" is removed.

Screenshots

Applicable Versions:

• Decap CMS version: 3.10.1
• Git provider: GitHub
• OS: using Dockerfile jekyll/minimal:3.8
• Browser version: safari 26.3.1 (21623.2.7.11.7)

• Node.JS version: n/a

CMS configuration

locale: 'fr'
slug:
  encoding: "ascii"
  clean_accents: true
  sanitize_replacement: "_"

backend:
  name: github
  repo: biothermica/biothermica-2026
  branch: master
  base_url: https://app.staticauth.com
  auth_endpoint: /auth/github/repo/69a8ca192824f5bdecb860ee

media_folder: "docs/media"
public_folder: "/media"

collections:
  - name: 'articles'
    create: true
    label: 'Articles'
    folder: 'docs/_articles/_posts/'
    slug: '{{year}}-{{month}}-{{day}}-{{slug}}'
    summary: '{{year}}-{{month}}-{{day}} - {{title}}'
    fields:
      - label: 'Titre en français'
        name: 'title'
        widget: 'string'
      - label: 'Titre en anglais'
        name: 'title_en'
        widget: 'string'
        required: false
      - label: 'Contenu en français'
        name: 'body'
        widget: 'markdown'
        required: false
      - label: 'Contenu en anglais'
        name: 'body_en'
        widget: 'markdown'
        required: false
      - label: 'Documents en français'
        name: 'documents'
        widget: 'list'
        required: false
        field: {label: Document, name: document, widget: file, required: false}
      - label: 'Documents en anglais'
        name: 'documents_en'
        widget: 'list'
        required: false
        field: {label: Document, name: document, widget: file, required: false}
      - label: 'Redirects en français'
        description: "Ajouter des redirections pour les anciennes URL de cet article. Par exemple: /fr/ancien-article"
        name: 'redirects'
        widget: 'list'
        required: false
        field: {label: Redirect, name: redirect, widget: string, required: false}
      - label: 'Redirects en anglais'
        description: "Ajouter des redirections pour les anciennes URL de cet article. Par exemple: /en/old-article"
        name: 'redirects_en'
        widget: 'list'
        required: false
        field: {label: Redirect, name: redirect, widget: string, required: false}

Additional context