Moves are not deletions for stamp attribution; re-stamp on move

Resolves the 06-vs-08 contradiction: 06's Lanework External fallback
demotes on true deletions only (id vanished from the board, per the
message engine's whole-board id matching), not folder moves. A bare mv
leaves the moved card unstamped, so 08 now teaches re-stamping on every
move as well as every write.

Claude-Session: https://claude.ai/code/session_01HJ7PhFNmQ19bvy9RMD6GSb

DESIGN/06-history-undo.md

@@ -50,7 +50,7 @@ Agent and hand edits arrive through the watcher like any change and get auto-com
 
 **Where the user's git identity comes from** (no git install is assumed, and the sandbox doesn't read `~/.gitconfig` — honest limits, not bugs): **repo-local `.git/config` wins when present** — standard git semantics, readable in-sandbox because it lives under the board root, and the natural state of adopted/cloned boards. The board popover's git section exposes name/email fields that **write that repo-local config** — the setting *is* the file, portable to any git client, per-board by nature (work and personal boards can differ). Absent repo config, the **derived default** applies: the macOS account's full name plus `shortname@hostname` — git's own no-config fallback shape, zero ceremony. Commits pushed to a forge under the derived email won't link to a forge account; the popover fields are the fix when that matters. A debounce window containing both kinds is **split into two commits**, never mixed (flush-before-overwrite already orders them: foreign first, then the user's overwrite). Honest limit: the app distinguishes app-mediated from foreign, not human from agent — a hand edit in a text editor and an agent write look identical *unless the writer says otherwise via `modified-by` (below)*. Agents wanting precise attribution are encouraged (via the agent guide, 08-agent-integration.md) to commit their own changes; the app follows along.
 
-**`modified-by` refines foreign attribution** (the self-reported provenance key — 01-storage-format.md): when every file changed in a foreign debounce window carries the same `modified-by: X`, that commit is authored as **X** with the synthetic email `<slug>@agents.lanework.invalid` (display name verbatim, email local part slugified; the domain marks self-reported identity, distinct from both the user and the generic external author). Any disagreement between stamps, any unstamped changed file, or any folder deletion in the window falls back to `Lanework External`. Same trust level as self-committing — it's what the writer claims, accepted as such; the stale-stamp hand-edit case (01) is the known misattribution edge. Self-committing remains the precise path; the stamp is the lightweight middle.
+**`modified-by` refines foreign attribution** (the self-reported provenance key — 01-storage-format.md): when every file changed in a foreign debounce window carries the same `modified-by: X`, that commit is authored as **X** with the synthetic email `<slug>@agents.lanework.invalid` (display name verbatim, email local part slugified; the domain marks self-reported identity, distinct from both the user and the generic external author). Any disagreement between stamps, any unstamped changed file, or any true deletion in the window falls back to `Lanework External` — a deletion leaves no file to stamp. **A folder move is not a deletion**: items match by id across the whole board (Commit messages above — the same matching that reads a move as a move, not delete+add), so a moved card attributes by its stamp like any changed file. But a bare `mv` rewrites nothing — the moved `index.md` still carries whatever the app last wrote (no stamp) and demotes the window under the unstamped-file rule — so the agent guide teaches re-stamping on move (08-agent-integration.md). Same trust level as self-committing — it's what the writer claims, accepted as such; the stale-stamp hand-edit case (01) is the known misattribution edge. Self-committing remains the precise path; the stamp is the lightweight middle.
 
 **Two writers, one repository — the designed situation, not an edge case.** Self-committing agents mean the auto-committer shares the repo with concurrent `git` processes, and it must be graceful about it: