feat: v2.7.8 — Artifacts hub, clone related repos as extra folders, quieter resume prompt

- Artifacts (/artifacts): claude.ai pages sessions publish (captured from the
  Artifact tool's hook), pinned workspace files, skills and plugins, each
  kept as a snapshot; shared ones appear in a Hub and a skill or plugin
  installs into the viewer's own account (server/lib/artifacts.js,
  /api/artifacts, docs/plans/artifacts/).
- Workspace extra folders: clone one or more related repos beside the
  workspace and add them in one step (POST /api/lanes/:id/sources/clone).
- A pane that ended by itself while tmux kept running is no longer offered
  for resume (tmux.serverStartedAt in reconcileOrphans).
- Changes panel: a folder that is not a git repo opens on Files, and its
  files open from there.
- Plus the parallel sessions' work in this tree: File Explorer button in the
  panel header, user delete, RSA SSH keys, chat/terminal and pet fixes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/plans/artifacts/README.md

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+# Artifacts hub — plan
+
+_Drafted 2026-10-14. Status: all three phases built 2026-10-14 (the session view's own Artifacts tab is not built; the page has the per-workspace file picker)._
+
+## Goal
+
+One place to keep what agents PRODUCE, and (in server mode) to share it:
+
+| Kind | What it is | Where it comes from |
+|---|---|---|
+| `page` | A claude.ai Artifact a session published (`claude.ai/…/artifact/…`) | the `Artifact` tool's PostToolUse hook, or a link pasted by hand |
+| `file` | A file an agent wrote (HTML, Markdown, PDF, image, CSV, Office…) | Write/Edit/NotebookEdit hook events, kept on the user's pin |
+| `skill` | A Claude Code skill folder (`SKILL.md` + files) | the user's own `~/.claude/skills/<name>` or a workspace's `.claude/skills/<name>` |
+| `plugin` | A plugin by marketplace source + name (no files) | the user's installed plugins (`claude plugin list`) |
+
+- **Local mode:** one personal library, no sharing UI.
+- **Server mode:** every artifact is the OWNER's and private by default. The owner can **Share** it; a shared artifact appears in the **Hub** for every signed-in user. A shared skill or plugin can be **installed** into the viewer's own account.
+
+## Rules (binding, same spirit as CLAUDE.md)
+
+- **What is shared is a SNAPSHOT, never the owner's live file.** Sharing a `file`/`skill` copies it (size-capped, regular files only, no symlinks followed) into `<data dir>/artifacts/<id>/`, written once like `session_snapshots`. Viewers read only that copy, so no route ever reads another user's home for them. Re-sharing makes a new snapshot.
+- **Nothing shared runs on the dashboard's origin.** HTML/SVG previews are served under the `/git/raw` headers (`sandbox` CSP + `nosniff`) and shown in a sandboxed iframe; a `page` is only a link out, accepted only as `https://claude.ai/…`.
+- **Installing is the viewer's explicit click, into the viewer's own account only.** For a skill, the hub writes the snapshot's files into `~/.claude/skills/<name>/` of the VIEWER (S3: as their member, through `write-as`). It never overwrites an existing skill without `conflict: replace`, and the old one goes to the trash first. For a plugin, the hub runs `claude plugin marketplace add <source>` + `claude plugin install <name>@<market> --scope user` as the viewer (the `applyPluginBaseline` path). The marketplace source passes an allowlist (`owner/repo` or a `validateRemoteUrl` URL), and no argv comes from the request beyond those two validated values.
+- **Before installing, the dialog lists every file of the skill** (a skill may carry scripts that the viewer's agent will run). Every share, unshare and install is written to `audit_log`.
+- **Visibility follows ownership:** a developer sees their own artifacts plus shared ones; admin/analyst see per `scope.js`, like sessions. Unshare removes an artifact from the Hub but does not uninstall copies others already installed.
+
+## Data
+
+New table `artifacts` (`CREATE TABLE IF NOT EXISTS` in `server/db.js`):
+
+`id, kind, title, description, owner_id, lane_id, session_id, source (path | url | market spec), url, snapshot (dir name | NULL), size, shared (0/1), shared_at, installs, created_at, updated_at`, plus an index on `(owner_id, kind)` and on `(shared, kind)`.
+
+## Phases
+
+1. **Library (local + server, private).** Table, `server/lib/artifacts.js`, `/api/artifacts` (list/get/create/patch/delete). `page` rows are captured from the `Artifact` PostToolUse hook (URL taken from `tool_response` by an `https://claude.ai/…artifact/…` match). `file` candidates are listed per workspace from Write events with a document extension, and the user pins them. New **Artifacts** page (sidebar) plus an **Artifacts** tab in the session view's right panel. Scope wiring: `PATH_RULES`, `broadcastAudience`.
+2. **Hub (server mode).** Share/Unshare buttons, snapshot, `Hub` tab, sandboxed preview, download, `artifact_shared` broadcast.
+3. **Skills & plugins.** "Share a skill/plugin" picker, the install flow (S3 included), conflict handling, audit.
+
+Each phase ships with its server and client tests and an update to `docs/API.md`.
+
+## Open questions
+
+- No `Artifact` tool call has happened on this machine yet, so the exact hook payload of a publish is unverified. Phase 1 matches the URL loosely and keeps "paste a link" as the fallback.
+- Should an admin be able to disable Hub installs for everyone (one switch in Settings)? Proposed: yes, on by default.