Unified Web `@file` and `@session` source. The browser starts the `fileReferences/list` and `sessionReferenceResolver/candidates` Remote calls together for an unquoted token, deterministically orders files before sessions with locale-registered folder/file/session labels, and renders the rows under non-selectable file and session section headings without a redundant raw `reference` source title. Either failed candidate domain degrades independently. An open `@"…` token searches files only.
File picks preserve the natural text defined by the shared `@path` grammar as their hidden serialized and clipboard form. A file closes completion as an atomic inline reference displayed with a file glyph, business-color filename, and no capsule. A directory remains plain editable path text with a folder glyph and keeps the menu active at its trailing slash so the user can descend another level. Paths containing whitespace use `@"path with spaces"`, and a quote the user opened explicitly remains quoted.
Session picks insert an atomic inline reference whose hidden `ref` and clipboard representation are the canonical `@[label](dsh-session:…)` mention returned by the Host. Its visible form is a chat-bubble glyph plus the business-color session title, without a capsule; serialization never reconstructs identity from that title. Ordinary send carries the canonical mention through `session.prompt`; the session-reference service validates it and captures model context at `agent/pre-step`.
Candidate browsing has no model effect. A selected file or session changes only the new user-message suffix and any Host-prepared session-reference context that follows that message; earlier target history remains unchanged.
- **Candidate failure is intentionally quiet** — one unavailable or failed Remote discovery call yields no rows for that domain. A session-reference preparation failure occurs after prompt acceptance and terminates that agent turn.
- **No browser-side file scan** — Web completion requires a mounted Host `ctx.fileReferences` provider; the browser cannot fall back to its own filesystem.
- **Session search remains metadata-only** — discovery filters session id, cwd, and the latest log-backed title through `ctx.sessionReferenceResolver`; message bodies and full transcripts are not searched.
