feat(web): quick start a new session from a directory

[Shujakuinkuraudo]

Feature Request

Support quickly starting a new HAPI session from a chosen directory.

Problem

When the user already knows the target project path, creating a session still requires going through the full new-session flow and manually entering or re-selecting the directory. This is slow on mobile and when switching between frequently used repositories.

Suggested Behavior

• Add a quick action from directory-oriented surfaces, such as recent directories, machine/project directory lists, or the directory picker.
• Reuse the user’s last/default agent, model, and permission mode where possible.
• Keep the existing approval flow for creating a directory when the path does not exist.
• After the runner successfully spawns the session, navigate directly to the new session.

Why

This would make remote spawn feel closer to "open this folder in HAPI", reducing repeated setup for common project directories.

[github-actions]

This is feasible, and most of the backend plumbing already exists. What is present today:

• /browse lets a user pick a workspace directory, but its Start Session button navigates to /sessions/new with directory and machineId prefilled; it does not directly spawn the session.
• /sessions/new can spawn a session for a selected machine/directory and navigates to the new session after success.
• Recent paths exist, but tapping one only fills the directory input; it still requires pressing Create.
• The new-session form remembers the last agent and YOLO toggle, but I did not find persisted defaults for model, Claude effort, Codex reasoning effort, or full permission mode.
• Missing-directory confirmation is already handled in the new-session flow before spawn.

So the missing product piece is a quick-start action that calls the existing spawn path directly from a directory-oriented surface, probably reusing the current new-session state/defaults where available and falling back to defaults where not persisted.

Relevant code:

• web/src/components/WorkspaceBrowser.tsx:191 - Start Session action for the current browsed directory.
• web/src/router.tsx:478 - browse page currently routes to /sessions/new with { directory, machineId } instead of spawning directly.
• web/src/router.tsx:406 - new-session success flow invalidates sessions and navigates to the spawned session.
• web/src/router.tsx:599 - /sessions/new accepts directory and machineId search params.
• web/src/components/NewSession/index.tsx:261 - create flow checks path existence, handles missing-directory confirmation, then spawns.
• web/src/components/NewSession/index.tsx:285 - spawn call passes machine, directory, agent, model/effort values, YOLO, and session type.
• web/src/components/NewSession/DirectorySection.tsx:77 - recent paths render as buttons that only select the path.
• web/src/hooks/useRecentPaths.ts:33 - recent paths are stored per machine, max 5.
• web/src/components/NewSession/preferences.ts:3 - only preferred agent and YOLO mode are persisted for new sessions.
• web/src/hooks/mutations/useSpawnSession.ts:30 - web spawn mutation calls api.spawnSession.
• web/src/api/client.ts:408 - API client posts spawn requests to /api/machines/:id/spawn.
• hub/src/web/routes/machines.ts:36 - hub spawn endpoint validates and forwards spawn data.
• hub/src/sync/rpcGateway.ts:123 - hub forwards spawn to the machine RPC handler.
• cli/src/api/apiMachine.ts:248 - CLI machine RPC validates workspace-root scope before spawning.
• cli/src/runner/run.ts:246 - runner creates missing simple-session directories after approval flow has allowed creation.

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HAPI Bot