Replace the three hardcoded host→guest credential syncs (opencode,
claude, pi) with a generic `[[file_sync]]` config list. Default is
empty — users opt in to exactly what they want synced, with no
surprise about which tools banger "supports".
```toml
[[file_sync]]
host = "~/.local/share/opencode/auth.json"
guest = "~/.local/share/opencode/auth.json"
[[file_sync]]
host = "~/.aws" # directories are copied recursively
guest = "~/.aws"
[[file_sync]]
host = "~/bin/my-script"
guest = "~/bin/my-script"
mode = "0755" # optional; default 0600 for files
```
Semantics:
- Host `~/...` expands against the host user's $HOME. Absolute host
paths are used as-is.
- Guest must live under `~/` or `/root/...` — banger's work disk is
mounted at /root in the guest, so that's the syncable namespace.
Anything outside is rejected at config load.
- Validation at config load: reject empty paths, relative paths,
`..` traversal, `~user/...`, malformed mode strings. Errors name
the offending entry index.
- Missing host paths are a soft skip with a warn log (existing
behaviour). Other errors (read, mkdir, install) abort VM create.
- File entries: `install -o 0 -g 0 -m <mode>` (default 0600).
- Directory entries: walked in Go; each source file is installed
with its own source permissions preserved. The entry's `mode` is
ignored for directories.
Removed (all dead after this):
- `ensureOpencodeAuthOnWorkDisk`, `ensureClaudeAuthOnWorkDisk`,
`ensurePiAuthOnWorkDisk`, the shared `ensureAuthFileOnWorkDisk`,
their `warn*Skipped` helpers, `resolveHost{Opencode,Claude,Pi}AuthPath`,
and the work-disk relative-path + default display-path constants.
- The capability hook registering the three syncs now calls the
generic `runFileSync` once.
Seven tests exercising the old codepath deleted; six new tests cover
the new runFileSync (no-op on empty config, file copy, custom mode,
missing-host-skip, overwrite, recursive directory). Config-layer
test adds happy-path parsing and a case-per-shape table of invalid
entries (empty, relative host, guest outside /root, '..' traversal,
`~user`, bad mode).
README updated: replaces the "Credential sync" section with a
"File sync" section showing the new config shape.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>