> ⚠️ **Postponed pending approval.** Part of the [Chat Fundamentals plan](https://git.drupalcode.org/project/ai/-/work_items/3586640); awaits maintainer approval ([approval issue](https://git.drupalcode.org/project/ai/-/work_items/3586639)). Targets the **1.6.x branch once it is created**. **Depends on:** [content blocks + `_meta` registry (#3586643)](https://git.drupalcode.org/project/ai/-/work_items/3586643), [structured response channel (#3586644)](https://git.drupalcode.org/project/ai/-/work_items/3586644), [renderers (#3586645)](https://git.drupalcode.org/project/ai/-/work_items/3586645). ### Problem/Motivation No citations or sources concept exists anywhere in the ai module — a RAG-backed assistant cannot show *where* an answer came from. The provenance is even actively destroyed today: ai_search's `RagAction::renderRagResponseAsString()` concatenates chunk text separated by `----------------------------------------` and discards entity IDs, URLs, scores and titles before the LLM ever sees the context, so the only "citation" a user can get is whatever markdown link the model happens to hallucinate or reproduce. Suggested replies (one-tap follow-up chips) have the same shape of problem: no contract, so any chatbot that wants them invents a frontend-specific hack. MCP (2025-06-18) has **no citations primitive**, so this issue codifies conventions on top of the shapes the plan already adopts, rather than inventing new block types that would break naive MCP consumers. ### Proposed resolution **Citations — a two-tier, spec-pure convention:** 1. **Sources** are plain `resource_link` content blocks on the answer message: `{type: "resource_link", uri, name, title?, description?}` with `annotations: {audience: ["user"], priority: <0..1 for ordering>}`. Any MCP-aware frontend renders a source list with zero Drupal knowledge; Drupal entities use `entity:` URIs and render as entity cards via #3586645. 2. **Inline anchors** (optional richness) live in `_meta['drupal.org/ai.citations']` on the *text* block: ```json [{"sourceUri": "entity:node/5", "citedText": "…", "startIndex": 120, "endIndex": 188}] ``` where `sourceUri` references a sibling `resource_link.uri`. Degradation is graceful by construction: a frontend that ignores `_meta` still shows the source list; a smart one adds footnote markers. (A custom `type: "citation"` block was considered and rejected — it would break the "MCP shapes only" invariant.) The streaming contract from #3586644 — the manifest's text block mirrors the streamed text — is what gives `startIndex`/`endIndex` a stable target. **Suggested replies — message-level `_meta`:** - `_meta['drupal.org/ai.suggested_replies'] = [{"label": "Show me more", "message": "Show me more results like the second one"}]` — `label` is what the chip displays, `message` (optional, defaults to label) is what gets sent when tapped. Submission is entirely the consumer's job; the contract only defines the payload. **Registry + emission:** - Register both keys in the `_meta` key registry (#3586643). - Make the assistant pipeline emit sources where it already holds provenance: the AI Assistant processor exposes them through `getStructuredResponse()` (#3586644), sourcing from action result metadata/structured results it already collects. A follow-up in ai_search should make `RagAction` retain chunk provenance (entity ID, URL, score) alongside the concatenated context so real source blocks can be emitted — that change is out of this issue's scope but is the natural next consumer. - Ship a `SourceListRenderer` refinement of #3586645's `ResourceLinkRenderer`: groups a message's source blocks into one themed, ordered source list (Twig template, overridable). **Tests:** unit validation of both `_meta` payload shapes; kernel test that a fixture processor emitting sources + anchors + suggested replies round-trips through `getStructuredResponse()` and renders via `SourceListRenderer` with correct ordering by `priority`. ### Backwards compatibility Pure conventions plus additive emission; nothing existing changes. Messages without these `_meta` keys behave exactly as today. ### AI Assistance Yes, AI was used to explore the codebase and draft this issue.