### Problem Canvas stores each static component input in a "collapsed" form. The rule is in `StaticPropSource::denormalizeValue()`: - If the prop's field type has one stored property, then the value is stored as a scalar. Example: a `string` prop is stored as `"Hello"`. - If the field type has more than one stored property, then the value is stored as a mapping. Example: a `link` prop is stored as `{uri: …, options: {}}`; a formatted text prop as `{value: …, format: …}`. No code checks that stored data follows this rule. If a scalar is stored where a mapping is required, then: - Validation passes. `$entity->getTypedData()->validate()` returns 0 violations. - Rendering works. `uncollapse()` calls `StaticPropSource::withValue()`, which calls core's `FieldInputValueNormalizerTrait::normalizeValue()`. That converts the scalar to `[main_property => value]`. For formatted text it also adds a default `format`. - The TMGMT extractor fails. `ComponentInputsTranslatablesExtractor::extractTranslatablesOptionallyIncludingEmpty()` reads the raw stored value, not the normalized one. When the schema element is a mapping and the stored value is a string, line 247 calls `extractTranslatables()` with a string and PHP reports: ``` TypeError: ComponentInputsTranslatablesExtractor::extractTranslatables(): Argument #2 ($config_data) must be of type array, string given, called in ComponentInputsTranslatablesExtractor.php on line 247 ``` Because the listing of config layouts calls the extractor for every layout, one invalid layout makes TMGMT config translation and Canvas Translate unusable for all layouts. This is not specific to links. The same happens for every field type with more than one stored property: `link`, `text`, `text_long`, `text_with_summary`, `image`, `daterange`. I reproduced it with a link prop and with a formatted text prop on the same page variant. The result is the same error. ### How a wrong shape gets stored Two ways. Both have occurred in shipped Drupal CMS site templates. **1. Hand-written or generated config.** Dashi's `canvas.page_variant.theme_dashi_theme.yml` contained `link_url: /about-dashi` for a `link` prop. Fixed in Dashi. **2. A prop's field type changes after content exists, and the content is then exported and imported.** Haven's "Page not found" page contained `href: /` (fixed in [#3591768](https://www.drupal.org/project/haven/issues/3591768)). The sequence: - The page was created and exported while `href` was a `string` prop. At that point `href: /` was the correct shape. - `DefaultContentSubscriber::preExport()` removes `component_version` from every exported instance. The code comment states that if the component changed in incompatible ways, the import will fail. - The theme then added `format: uri-reference` to `href`. As a result the prop's field type is `link`, and the component's active version changed. - On import, if an instance has no `component_version`, then `ComponentTreeItem::onChange()` assigns the active version. The scalar `href: /` is now stored under a version whose field type is `link`. - The import does not fail, because of the lenient normalization described above. So the comment in `preExport()` does not match the actual behavior. `JsonSchemaPropsComponentInstanceUpdater::canUpdate()` returns FALSE when a prop's shape changed between versions. The default content import path does not use that check, so it does not get that protection. No standard tool reports the problem. `drush content:export` writes the stored scalar unchanged. The value is only rewritten in the correct shape if the page is saved again in the editor. `canvas doctor` has no check for stored value shapes. ### Steps to reproduce Short version, Canvas 1.12.0, any SDC with a prop that has `format: uri-reference`: 1. Create a page variant or content template that uses that component. In the YAML, set the link prop to a string, for example `link_url: /about`. Import the config. 2. Call `$variant->getTypedData()->validate()`: 0 violations. Load the page: it renders. 3. Install `tmgmt` and `tmgmt_config`, or Canvas Translate. Open config translation for that layout. Result: the TypeError above. 4. Repeat with a formatted text prop set to `text: '<p>Hi</p>'`. Same error. Longer version, matching the Haven case: create a page with a component whose prop is `type: string`; export it with default content; add `format: uri-reference` to that prop in the theme; import the content. Same error. ### Proposed resolution Make the storage rule a validation constraint, so that invalid shapes cannot be stored: 1. Add a constraint on component tree inputs. For each static input: if the prop's field type has one stored property, then the value must be a scalar; if it has more, then the value must be a mapping (or a list of mappings for multi-value props). Use the same property count as `denormalizeValue()`. Entity save, config import, and default content import all run validation, so this covers both cases above. 2. On default content import, when `onChange()` assigns the active version, apply the same compatibility check as `canUpdate()`. If the shape changed, then either convert the value with `uncollapse()` followed by `collapse()`, or reject the import with a clear error. 3. Change `ComponentInputsTranslatablesExtractor` to read values through `uncollapse()` instead of the raw stored data. Then one invalid layout no longer breaks translation for all layouts. This is optional once item 1 exists. 4. Add a `canvas doctor` check for existing data, so that sites can find values stored before the constraint existed. The lenient `normalizeValue()` read can stay. If invalid shapes can no longer be stored, then it has no harmful effect. ### Remaining tasks - Agree on items 1–4. - Constraint and tests for `link`, formatted text, `image` and `daterange` props, in both directions: scalar where a mapping is required, and mapping where a scalar is required. - Import-path check and a test with an exported page whose prop type changed. - Doctor check. - Correct the comment in `DefaultContentSubscriber::preExport()`. ### User interface changes None. ### API changes A new validation constraint on component tree inputs. Existing config and content with invalid shapes will fail validation after the change. The doctor check (item 4) is how a site finds those values first. ## LLM disclosure Bug was found with an LLM and writeup was supported by an LLM.