feat: support all BFM formats in both inline and block reference directives

[lukemelia]

Resolves CS-11704.

Why

BFM previously coupled render format to placement: the inline directive :card[url] had no size/format slot, so it was hardcoded to atom; only the block directive ::card[url | spec] could express embedded / fitted / isolated / dimensions. This decouples format from placement so every format works in both modes — the grammar ("dictionary") side of the Markdown Editing UI design.

What changed

Grammar — packages/runtime-common/bfm-card-references.ts

• parseBfmSizeSpec accepts atom (and confirms embedded/isolated); BfmSizeSpec.format gains 'atom'.
• Inline tokenizer splits the bracket on | and captures the specifier; inline renderer emits data-boxel-bfm-format / -width / -height via a new shared bfmSizeAttrs helper used by both the inline and block renderers.
• extractBfmReferences strips the specifier from inline URLs (so :card[url | spec] extracts just the URL).
• bfmBlockFormatAndSize → bfmRefFormatAndSize (BfmBlockFormat → BfmRefFormat, now includes atom) with a defaultFormat param — block defaults to embedded, inline to atom.

Writer — packages/base/markdown-helpers.ts

• markdownEmbedForCard honors the size option for inline embeds (:card[id | embedded]).

Renderers — packages/host/.../rendered-markdown.gts + packages/base/default-templates/markdown.gts (kept in parallel)

• Inline refs derive format/size from the data attributes instead of forcing atom. Resolved non-atom inline slots flow as display: inline-block (new --inline-embed class); loading/broken inline placeholders adopt the derived footprint. Plain (atom) inline refs are unchanged.

Docs — updated the dev-bfm-syntax and dev-markdown-format skill grammar tables to document inline specs and the atom spec.

Acceptance criteria

• :card[url | embedded], :card[url | 400x200], and ::card[url | atom] all parse, extract, and render in the correct format and placement. ✅

Scope note (read/grammar side only)

This is the partial-on-main slice agreed for CS-11704. The literal serializeBfmRef function and the markdown-embed-preview-pane test referenced in the ticket live only on the open PR #5303 (cs-11673) branch, not on main, so they're deferred. On main the writer is markdownEmbedForCard (which #5303 turns into a serializeBfmRef delegate); the inline-size logic added here moves into serializeBfmRef as a straightforward conflict resolution when #5303 lands, after which the chooser emits/previews inline-formatted embeds with no further change.

Tests

• Unit (bfm-card-references-test, markdown-helpers-test): inline pipe-extraction, inline renderer emits format/size attrs, parseBfmSizeSpec('atom'), bfmRefFormatAndSize atom + defaultFormat, block | atom, "ignored for inline" flipped to "honored for inline".
• Integration (rendered-markdown-test): inline embedded/fitted/atom data-attr + broken-footprint cases.
• Integration (rich-markdown-field-test): real-card resolved inline embed asserts the --inline-embed (inline-block) slot class; atom ref keeps --inline.

Verified locally with ember-tsc (host + runtime-common), eslint, and ember-template-lint. The host QUnit suite runs on CI.

🤖 Generated with Claude Code

[github-actions]

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Host Test Results

    1 files      1 suites   2h 0m 35s ⏱️
3 191 tests 3 176 ✅ 15 💤 0 ❌
3 210 runs  3 195 ✅ 15 💤 0 ❌

Results for commit 1e153da.

Realm Server Test Results

    1 files      1 suites   11m 15s ⏱️
1 727 tests 1 727 ✅ 0 💤 0 ❌
1 820 runs  1 820 ✅ 0 💤 0 ❌

Results for commit 1e153da.

[Copilot]

Pull request overview

Decouples BFM render format from placement so inline (:card[...]) and block (::card[...]) directives can both express any supported format/size, with placement-specific defaults (inline → atom, block → embedded).

Changes:

• Extended BFM size parsing/extraction/rendering to support atom and inline | spec, emitting shared data-boxel-bfm-format/width/height attributes for both inline and block refs.
• Updated markdown writer helper (markdownEmbedForCard) to serialize inline embeds with an optional | size spec.
• Updated host + base markdown renderers to derive inline slot format/footprint from data attributes and render non-atom inline embeds as inline-block (with matching loading/broken placeholders), plus added/updated tests and docs.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/runtime-common/bfm-card-references.ts	Adds atom size parsing, inline `
packages/base/markdown-helpers.ts	Allows inline embeds to include `
packages/host/app/components/operator-mode/preview-panel/rendered-markdown.gts	Derives inline format/footprint from BFM data attrs; adds inline-embed slot/loading/broken behaviors and styles.
packages/base/default-templates/markdown.gts	Mirrors host renderer changes for base realm markdown rendering (format derivation + inline-embed flow/styling).
packages/host/tests/unit/bfm-card-references-test.ts	Adds coverage for inline pipe URL extraction, inline/block attribute emission (including atom), and bfmRefFormatAndSize defaulting behavior.
packages/host/tests/unit/markdown-helpers-test.ts	Updates expectations so inline embeds honor size, and adds an inline embedded size test.
packages/host/tests/integration/components/rendered-markdown-test.gts	Adds integration coverage for inline size/format attrs and unresolved inline footprint behavior (embedded/fitted/plain).
packages/host/tests/integration/components/rich-markdown-field-test.gts	Verifies resolved inline embeds use --inline-embed for non-atom while atom keeps --inline.
packages/boxel-cli/plugin/skills/dev-bfm-syntax/SKILL.md	Documents inline `:card[URL
packages/boxel-cli/plugin/skills/dev-markdown-format/SKILL.md	Updates helper table to document inline `

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