DSH plugin right sidebar: tab types, routing and keepMounted

A DSH plugin does not "add a panel" to the right sidebar; it registers a tab type into a dock surface that has identity, routing and lifecycle. Three concepts decide everything: each session has exactly one dock surface (stored in a session-scoped slot store and restored after refresh); tab identity is (kind, address) (same type and address reuse, different types coexist); and routing is an ordered claim (priority tier, then longest pattern, then registration order). Layer keepMounted for lazy keep-alive and canOpen for a synchronous veto, and you control both "who may open this address" and "does the body survive a switch."

DSH plugin right sidebar: one dock surface per session

Bottom line: one surface per session, stored in a session-scoped slot store, restored after refresh.

1. Composition: a column of panes and tabs beside the conversation, with address-addressed content that can open, split, float and close.
2. Ownership: the sidebar package owns the surface, the tab type registry and the navigation service; the layout engine is an internal dependency.
3. Root controller: keeps separate seats for the selected session and for background sessions with initialized keepMounted bodies, but only the foreground session is visible.
4. Change records: every surface change is one history record from a pure planner.
5. No empty panes: an empty root pane is automatically filled.

DSH plugin addresses and tab identity

Bottom line: callers supply resource addresses, the sidebar writes page addresses, and identity is (kind, address).

1. Resource scoping: the file protocol starts with session/<id> or absolute.
2. Do not assemble page addresses: use openTab('guide') or openTab('files').
3. Identity rule: same address through the same type reuses a tab; through two types it creates two.
4. contentId: the claim records the address verbatim.
5. No other navigation addresses exist.

DSH plugin pane-tab registration: seven fields

Bottom line: the definition is static, with no runtime hooks and nothing per-tab or per-session.

1. Register inside an effect: ctx.sidebarRightTabs.register(definition).
2. Duplicate ids throw.
3. Glob details: patterns containing : match the whole address; others match only the URL path portion at any depth; case-insensitive, dotfiles not hidden, picomatch POSIX syntax.
4. Extension takeover: one kind may hold both a builtin and an extension, and the builtin returns when the extension unregisters.
5. Guide entry: an optional guide box that opens the contributing type as a page.

DSH plugin routing: an ordered claim

Bottom line: tier, then longest matching pattern, then registration order; no claimant throws as a wiring error.

1. Candidates: candidates(address) filters matching types not vetoed by canOpen.
2. Sorting: priority tier first, then longest matching pattern, then registration order.
3. Claim: claim(address, kind?) takes the first candidate; a named kind skips globs but still honors canOpen.
4. Result: { kind, contentId: address, title }.
5. Unclaimed addresses throw: that means no type can handle the address — a wiring error, not a user action.

DSH plugin keepMounted and the guide

Bottom line: keep-alive applies only to visited bodies; guide boxes are a type's own entry points and take no tab.

1. Scope: visited bodies survive hiding, session switches and dock switches while their View holds the session reference.
2. No pre-mounting: unvisited bodies never render just because keepMounted is set.
3. Pairing with resources: the sidebar pins an open tab's address for the tab's lifetime, so switching tabs does not close streams.
4. Guide shape: { order, title(), description?, icon? }; clicking opens the type as a page.
5. Verify: switch away and back to confirm the body survives, and confirm new tabs are not kept alive.

DSH plugin right sidebar troubleshooting

Bottom line: separate no claimant, wrong claimant and body not kept alive.

1. Opening throws — no type claims the address; check patterns and canOpen.
2. Wrong type opens — check priority tier and pattern length; extensions beat builtins by default.
3. Two tabs for one address — two kinds opened it; identity is (kind, address).
4. State lost after switching — keepMounted is off or the body was never visited.
5. Duplicate registration — the same id is registered twice.
6. Repair status, stated honestly: address rules, registration fields, three-tier ordering and keep-alive semantics follow the official Right sidebar page; confirm extension slots and built-in types against that page and the package README.

Sources: Right sidebar, dsh-client-ui-sidebar-right README, Client resources.