docs(roadmap): add Projects System Evolution section

Captures the backlog discussed during v2.3 planning so future
sessions can pick up items without re-deriving the terrain:

- v2.3 (planned, in this branch): folders + rename/archive/search
  + per-project Sessions tab via a sidecar attribution file.
- v2.4+: per-project activity feed, token rollup, cron filter,
  desktop notifications — all "filter existing data via the
  sidecar" work, unblocked once v2.3 ships.
- v2.5+: platform bets (Hermes upstream sessions.cwd column,
  per-project memory slice, per-project skills namespace,
  cross-project meta-dashboards, project backup/restore).
- Continuous polish: drag-and-drop, tags, favorites, recents,
  color labels, starter dashboards, opportunistic backfill.
- Known research gaps to chase when relevant.

No code change; pure docs. Commits to the feature branch
because the v2.3 planning context originated there; lands on
main with the merge.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scarf/docs/ROADMAP.md

@@ -56,3 +56,56 @@ Rich usage analytics pulled from the sessions and messages SQLite tables:
 
 ### 10. Config Editor
 - Structured form editor for config.yaml with validation
+
+---
+
+## Projects System Evolution (post-v2.2.1)
+
+A parallel backlog specific to the Projects feature. Ordered by dependency: organization first, then per-project attribution via sidecar, then observability built on that attribution, then polish, then platform bets.
+
+### Shipping in v2.3 (planned — plan file at `~/.claude/plans/`)
+
+- **Folder hierarchy in the sidebar.** `ProjectEntry` gains optional `folder: String?`. `DisclosureGroup`-based sidebar.
+- **Rename + archive + search.** Registry verbs + a fuzzy ⌘F search + soft-archive (`archived: Bool?`) with Show/Hide toggle.
+- **⌘1–⌘9 project jumps.**
+- **Per-project Sessions tab** alongside Dashboard / Site. Filters the global sessions list by a new `~/.hermes/scarf/session_project_map.json` sidecar that Scarf populates when it starts a chat with a project context.
+- **New Chat button** on the Sessions tab — spawns `hermes acp` with `cwd = project.path` and attributes the resulting session in the sidecar.
+
+### v2.4+ — per-project observability
+
+Depends on v2.3's sidecar being stable. All features below are "filter the existing data by the sidecar's project mapping."
+
+- **Per-project activity feed.** Extend `ActivityViewModel` with a `projectPath` filter that maps through the sidecar. Dashboard widget type `recent-activity`.
+- **Per-project token / cost rollup.** `InsightsViewModel.computeAggregates()` already sums over sessions; add a project filter. Widget binding `project.tokens` exposes it to agent-driven dashboards.
+- **Per-project cron-job filter.** Cron sidebar gains a project dropdown. Template-installed jobs already carry `[tmpl:<id>]` prefixes; match against installed template manifests to attribute.
+- **Desktop notifications for cron completion.** When a project-attributed cron job finishes (success or failure), fire a `UNUserNotification`. Per-project mute.
+
+### v2.5+ — platform bets
+
+Bigger investments with longer arcs.
+
+- **Hermes upstream: `sessions.cwd` column.** Propose adding a nullable `cwd` (or `workspace_id`) column to Hermes's sessions table, populated on session create. Scarf would prefer the canonical column when available and fall back to the sidecar for pre-upgrade sessions. Requires coordinated Hermes release; filed under platform bets because it cuts the sidecar's blind spot (CLI-started sessions never enter the sidecar today).
+- **Per-project memory slice.** Hermes reads `MEMORY.md` from a known path. Explore whether Scarf can spawn `hermes acp` with an overridden memory path (per-project `<project>/.scarf/MEMORY.md`) so projects get isolated context. Needs a Hermes-side env var or flag.
+- **Per-project skills namespace.** Today user-authored skills are flat under `~/.hermes/skills/`. A `~/.hermes/skills/project/<slug>/` namespace parallel to the existing `templates/` namespace would let users install skills *into* a project without a template. Uninstall = drop the folder.
+- **Cross-project meta-dashboards.** A portfolio view that aggregates widgets from multiple projects — total token spend, combined activity feed, project-health matrix. Useful at 20+ projects.
+- **Project backup / restore.** One-click zip of `<project>/` + sidecar entries + related Keychain secrets, restorable on another machine. Richer than the existing Export flow (which carries the template shape only).
+
+### Continuous — UX polish
+
+Small, shippable at any time. Each is a half-day-to-one-day item.
+
+- **Drag-and-drop to reorder** projects within a folder and between folders. Would be the first use of `.onDrag`/`.onDrop` in the codebase; establishes the pattern.
+- **Tags as a secondary axis.** Keep folders as primary, add multi-valued string tags + filter chips at the sidebar top. Decide only if folders feel insufficient after v2.3 lands.
+- **Favorites / pin** — bubble a project to the top of its folder.
+- **Recent projects collection** — auto-populated "Recents" row at the top of the sidebar.
+- **Color labels or SF Symbol icons** per project (Finder-tag-style).
+- **Project dashboard starter templates** — "blank", "monitor", "feed", "timeline" shapes when creating a bare project (distinct from `.scarftemplate` sharing flow).
+- **Opportunistic session backfill.** When Scarf loads any session that isn't in the sidecar, peek at first tool call's `working_directory` or `cwd` hint; if it matches a registered project path, write a sidecar entry. Heuristic, not perfect — useful as an "it just works" improvement after v2.3 ships.
+
+### Research / verification gaps
+
+Noted during v2.3 planning; chase when relevant:
+
+- `DisclosureGroup` inside `List(.sidebar)` on macOS — occasional animation glitches with many-rows-expanding. Early prototype will confirm before full commit.
+- Concurrent sidecar writers from multiple Scarf windows on the same `~/.hermes` — atomic replace handles per-write; reload behavior may lag. Acceptable; revisit if users report stale attribution.
+- Do Hermes sessions ever persist `cwd` anywhere in `state.db` today that we've missed? If so, we can skip the sidecar and use it directly. Worth a one-hour investigation before starting v2.4 observability work.