Interactive startup hangs forever (blank TUI, no timeout) when a plugin marketplace dir contains macOS File Provider dataless placeholders; plus silent infinite retry on rejected API key

# Claude Code bug report — interactive startup hangs forever on a plugin-marketplace directory containing macOS File Provider dataless placeholders

_Prepared 2026-08-13 (recovery session). File via `/bug` when convenient. All findings below are
empirical, two-sided-proven (removal cures + re-addition reproduces), from a multi-day diagnosis._

## Summary
If `settings.json` registers a **directory-source marketplace** (`extraKnownMarketplaces` with
`source.path`) whose install location lives on a **macOS File Provider volume** (Dropbox in
CloudStorage mode), and any files in that tree are **dataless placeholders** while the File
Provider daemon is unhealthy, **interactive `claude` hangs forever at startup with a fully blank
TUI** — no spinner, no timeout, no error, no log line. `claude -p` (non-interactive) does NOT
hang, which misdirects diagnosis toward TUI/terminal config for days.

## Environment
- Claude Code v2.1.228–v2.1.232, macOS Darwin 25.5.0 (Apple Silicon)
- Auth: Claude Max (keyless)
- Marketplace: directory source at
`/Users/leeromsegal/Dropbox/2026 Coding/Genome/klick-ai-playbooks`
(through the `~/Dropbox` symlink → `~/Library/CloudStorage/Dropbox-LeeromSegal/…`)
- Tree state: 273 files, of which 57 were dataless placeholders (`ls -lO` shows `dataless`),
while `fileproviderd` + the Dropbox File Provider extension were wedged (~100–200% CPU,
network counters frozen — materialization requests never serviced).

## Repro
1. Put a directory marketplace on a File Provider volume; evict part of it (or let the
provider keep it online-only).
2. Wedge or suspend the File Provider daemon (in the wild: the Dropbox FP extension spinning
in sqlite change-enumeration; simulatable with `kill -STOP` on the provider extension).
3. Register it in `settings.json` under `extraKnownMarketplaces` + enable a plugin from it
in `enabledPlugins`.
4. Launch interactive `claude` → permanent blank screen. Remove the two keys → instant paint.

## Two-sided proof (bisect over full config)
- Full config → BLANK. Config minus `env`/`tui`/`hooks`/`statusLine` (each) → still BLANK.
- Config minus `enabledPlugins`+`extraKnownMarketplaces` → PAINTED.
- Minimal config + only those two keys → BLANK. Same, with only the Dropbox-resident
marketplace entries stripped (other marketplaces kept) → PAINTED.
- Mechanism: a bare `cat` of one 11KB dataless file in that tree blocks >30s (unbounded);
Claude Code startup evidently performs equivalent blocking reads on the marketplace dir.
- Repointing the marketplace `source.path` to a fully-material local copy
(`~/dev/klick-ai-playbooks`), all other config byte-identical → PAINTED.

## Why this is worth fixing
- The failure is **silent and unbounded**: no timeout, no stderr, no entry in `claude doctor`
territory. A user whose cloud-sync daemon is unhealthy loses Claude Code entirely, with
zero pointer to the cause.
- `-p` mode completing normally actively misleads diagnosis (looks like a TUI/terminal bug).
- Dropbox/OneDrive/iCloud CloudStorage homes are common; any `.claude` asset (marketplace,
plugin, hook script) on such a volume can be a placeholder at any time.

## Suggested fixes (any one would have prevented days of outage)
1. **Bounded reads at startup**: wrap marketplace/plugin directory scans in a timeout
(even 10s), then degrade: skip the marketplace, print one warning line, continue.
2. **Dataless-awareness on macOS**: check for `SF_DATALESS`/`dataless` flag before open;
skip or async-hydrate rather than blocking the startup path.
3. **Startup phase logging**: a `CLAUDE_DEBUG=startup` breadcrumb ("loading marketplace X…")
would have named the culprit in one run instead of a multi-round settings bisect.
4. `claude doctor`: flag any configured path that resolves into `~/Library/CloudStorage`.

## Related earlier finding (same saga, distinct bug — already known internally?)
With `ANTHROPIC_API_KEY` exported but invalid/unfunded, `claude -p` silently retried forever
(rc never returned) instead of failing fast with an auth error. Keyless Max auth worked.
Fail-fast + a clear "API key auth failed" message would fix that leg.

Reproduce with settings.json using extraKnownMarketplaces and enabledPlugins pointing at the Dropbox/File Provider directory, then compare interactive claude with claude -p and inspect the proposed CLAUDE_DEBUG=startup path. Done means interactive startup no longer hangs indefinitely on dataless placeholders and invalid ANTHROPIC_API_KEY authentication exits with a clear error instead of retrying forever.

Written by the indexing model from the issue text.