[quickbeard]

A sandbox can mount several folders, but all of their sessions shared one tab strip on the Work side, so working across two folders meant constantly reading past the other one's tabs.

Mounted folders are already ordinary projects on the sandbox server — packages/app/src/sandbox/projects.ts:41 seeds one per mounts[].guestPath plus the primary — so the strip is now keyed by (sandbox, folder), with the sandbox's own project folder on equal footing with the extra mounts. Code is unchanged.

Behaviour

• Every folder of every sandbox keeps its own tabs.
• Clicking a folder in the sidebar goes to the session you were last in there, else that folder's open draft, else a new one — the chain the Code/Work switch already had, one level down.
• Tab shortcuts (mod+1…9, next/previous, mod+w) act within the folder on screen. Closing the last tab of a folder no longer drops you into an unrelated one.
• The same folder mounted into two sandboxes stays separate, and so do two sandboxes that both mount their project folder at /workspace.
• The Work strip now shows one sandbox at a time — a consequence of including the sandbox in the key, and a visible change from today.
• Existing tabs keep their place; anything not immediately matchable to a folder stays visible in its sandbox until it is.

Design

The scope is derived, never stored: folder on screen → sidebar's selected project → the sandbox's primary folder. This makes "the strip always contains the session you are looking at" true by construction instead of via an effect racing the two home effects in context/layout.tsx, so deep links, command-palette jumps and reopened tabs all pull the strip to their own folder. It also keeps the change to tabs only — writing the route's folder into home.selection.directory would feed projectDirectories() and silently narrow the sidebar's Recents.

Logic lives in the fork-only src/workspace/{side.ts,tabs.tsx}; tabsForSide/reorderWithinSide became thin wrappers over the same primitives so the Code path is provably the old one. Upstream files hold wiring only, recorded as one new row in DIVERGENCES.md.

SessionTab gains an optional directory, deliberately absent from tabKey() — that is what keeps every persisted info/memory/closed key valid as the field appears. Tabs that predate it recover from the info record the strip already writes for every tab it renders.

Drive-by fix

enter(side) read projects.list()[0] as the sandbox's folder, but projects.open() prepends, so that was whichever mount was added most recently rather than the folder the sandbox was created with. It now reads the guest cwd, matching sandbox/projects.ts:53.

Testing

• 663 unit + 90 browser tests pass, 21 new: folder resolution (/mnt/shared must not swallow /mnt/shared-2; deepest folder wins when folders nest), a regression lock proving a side scope equals the old side filter, two sandboxes both at /workspace staying separate, the primary folder not being privileged, unresolved tabs, tab identity preserved by reference (the strip compares by reference), reorder merges, the directory back-fill, and the folder-entry chain.
• 139 smoke + regression e2e tests pass in a real browser, including cross-server-tab-close, new-session-reuses-draft, sidebar persistence and terminal tab switching.
• bun typecheck clean in packages/app and packages/desktop.

Not verified end-to-end: the Work side running for real. The web e2e harness has no sandbox platform, so effectiveSide collapses it to Code — there is no way to drive Work there, which is why the repo has no Work-side e2e tests. folderEntry was extracted as a pure function to cover that decision chain directly. Still worth a manual pass before merge: create a sandbox, add a second folder via Settings → Servers → Folders…, open sessions in each, and check the strip, the folder switch, and the tab shortcuts.

🤖 Generated with Claude Code

[quickbeard]

Manual pass done — one real bug found and fixed

Drove the running desktop app (Electron dev build, page-level CDP on the remote-debugging port — Playwright's connectOverCDP hangs against Electron's browser-level endpoint) against an existing sandbox with four mounted folders: /workspace (primary, repos/opencode), /mnt/codev-hub, /mnt/codev-office, /mnt/vibe-coding, with three pre-existing Work session tabs spread across three of them.

Bug found: an empty draft was minted beside tabs that were already there

Selecting a folder that had open session tabs but no recorded last-session created a new draft instead of landing on one of its tabs. Every folder is in that state the first time it is opened after this ships, because lastFolderSession starts empty — so this was the common path, not an edge case. Observed directly: clicking codev-hub gave strip=[draft:b4509529*, ses_00032035…].

Fixed in a49a83b: folderEntry gains an openSession step between the folder's open draft and creating a new one, resolved through the same folders list the strip uses so the tab landed on is always one the strip will show. Tabs whose folder is still unknown are skipped — they appear in every folder of the sandbox, so picking one could jump elsewhere the moment it resolves. Work only; on Code the chain is reached from enter(side), where this step would change the side switch's behaviour.

Verified against the real app after the fix — 19/19

Isolation and folder switching (15/15), each folder checked twice, before and after it had recorded history:

• each of the three folders showed only its own tab, never the other folders' or Code's
• the folder's own tab was the active one
• no draft minted beside it
• codev-office (nothing open) correctly got a draft of its own, alone in the strip
• revisiting each folder returned to its remembered session
• Code showed only its own draft; returning to Work landed back on a single folder's strip

Keyboard shortcuts, in a folder holding two tabs (4/4): mod+t added a tab to the folder on screen; ctrl+tab cycled within the folder; mod+w closed the active tab and landed on its folder's neighbour rather than another folder's tab; the side stayed on Work throughout. mod+shift+t restored the closed tab into the right folder.

Migration verified on real pre-existing data

The three Work session tabs were persisted before SessionTab.directory existed. They came back carrying /mnt/vibe-coding, /mnt/codev-hub and /workspace, recovered from the tabs.info records the strip had already written — no tab vanished. After a graceful quit, both the back-filled directories and lastFolderSession were on disk:

"sandbox:codev-work\n/mnt/vibe-coding": "ses_00031e19…"
"sandbox:codev-work\n/mnt/codev-hub":   "ses_00032035…"
"sandbox:codev-work\n/workspace":       "ses_000f10f5…"

(An earlier kill -9 did lose that write — expected, since settings now write asynchronously per #237; the graceful path flushes them.)

Still not covered

Cross-sandbox isolation needs a second sandbox; only unit tests cover that the same guest path in two sandboxes stays separate. bun test is 663 unit + 92 browser green, bun typecheck clean in packages/app and packages/desktop.

🤖 Generated with Claude Code