Surface detached split-root state checkouts

[kentwelcome]

Make detached and other split-root checkout states visible so Spacetop can inspect available snapshots without overclaiming sync freshness.

What changed

• Add typed storage backend and checkout disposition models.
• Probe split-root Git topology with fail-closed path containment.
• Render topology diagnostics and truthful partial sync outcomes.
• Re-probe topology across reload, watcher, and sync paths.

Evidence

• 590/590 unit tests passed; all enabled integration and doc tests passed.
• 8/8 topology-sync and 7/7 topology/parser regressions passed.

Review guidance

Focus on state_checkout.rs path containment and lib.rs sync re-probe boundaries.

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076

Closes spacedock-dev/spacedock#677

[Copilot]

Pull request overview

This PR extends Spacetop’s split-root workflow support by classifying storage backend separately from the runtime Git checkout disposition (attached / detached / wrong-branch / missing / probe-failed). It then surfaces those topology diagnostics in the TUI and ensures sync/reload paths re-probe topology so Spacetop can remain read-only while still truthfully inspecting whatever snapshot is available.

Changes:

• Add typed models for workflow storage (WorkflowStorage) and split-root checkout disposition (StateCheckoutDisposition), plus a read-only topology probe (state_checkout.rs).
• Update parsing/indexing/sources to load entities+archives from the typed storage location, and surface topology diagnostics in the UI footer/help and sync outcomes.
• Add regression tests covering reload behavior, watcher relevance, UI stable strings, and verified-fast-forward sync boundaries.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
README.md	Updates user-facing docs to describe split-root backends, dispositions, and verified sync behavior.
docs/development-policy.md	Documents new topology classification responsibilities and verified-attached sync boundary.
AGENTS.md	Updates repo contract/code map to include split-root topology classification and verified state sync rules.
crates/spacetop-core/src/domain/mod.rs	Introduces WorkflowStorage and StateCheckoutDisposition into the typed domain model.
crates/spacetop-core/src/state_checkout.rs	Adds read-only storage classification + Git topology probing with containment checks.
crates/spacetop-core/src/parser/readme.rs	Parses state-branch: and classifies storage/topology during README parsing.
crates/spacetop-core/src/parser/snapshot.rs	Reuses split_root_entity_dir for entity-dir resolution (fail-closed behavior).
crates/spacetop-core/src/parser.rs	Removes direct export of the old resolve_entity_dir helper.
crates/spacetop-core/src/index.rs	Exposes storage via the workflow index for app/UI consumption.
crates/spacetop-core/src/sources.rs	Loads archives via the typed storage entity directory.
crates/spacetop-core/src/watcher.rs	Treats split-root state directory events as watcher-relevant.
crates/spacetop-core/src/lib.rs	Exposes the new state_checkout module publicly.
crates/spacetop-core/tests/state_checkout_fixtures.rs	Adds real-git fixture tests for attached/detached/wrong/missing and external symlink behavior.
crates/spacetop/src/app/overview.rs	Adds SyncStatus::SucceededWithState/Partial and app-layer topology diagnostics.
crates/spacetop/src/app.rs	Exposes workflow_storage() so sync orchestration can consult current typed storage.
crates/spacetop/src/lib.rs	Re-probes topology across sync and gates state sync to verified-attached split-root checkouts (plus new tests).
crates/spacetop/src/ui/footer.rs	Renders topology diagnostics and adds new sync pill variants/color mapping.
crates/spacetop/src/ui/help.rs	Updates help text to clarify “verified” fast-forward sync behavior.
crates/spacetop/src/ui/tests.rs	Adds helper to build App with explicit storage for UI diagnostic tests.
crates/spacetop/src/ui/tests/task_list.rs	Adds tests pinning stable footer diagnostics and new sync pill strings/colors; updates fixtures for storage.
crates/spacetop/tests/state_topology_reload.rs	Adds integration test that reload re-probes topology while keeping archive scope readable.
crates/spacetop/src/ui/tests/preview.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/ui/tests/paths.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/ui/tests/overview.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/ui/tests/chrome.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/ui/graph/tests.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/ui/definition.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/app/tests.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/app/mouse.rs	Updates test fixtures for new WorkflowDefinition.storage field.
crates/spacetop/src/app/keys.rs	Updates test fixtures for new WorkflowDefinition.storage field.

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[kentwelcome]

Fixed in 04b6b0d. I replaced the allocating label() -> String path with Display, so footer rendering writes the diagnostic directly into the final formatted string. The existing Ratatui topology-diagnostic test passes.

[kentwelcome]

Fixed in 04b6b0d. split_root_entity_dir now requires at least one normal path component, so ., ./, and ././ remain single-root even when state-branch: is set. A focused regression proves these forms trigger no Git probe; full tests and lint pass.