docs(windows): clarify portability rules

.github/AGENTS.md

@@ -1,3 +1,3 @@
-# AGENTS.md — CI gates
+# AGENTS.md — GitHub Actions
 
-Run Windows gates from native `pwsh`, invoke pnpm shell-free, and normalize repo-relative glob paths to `/` at ingestion. Keep platform fixes at each gate boundary; do not add a shared platform layer.
+Run Windows jobs under native `pwsh`.

packages/support/acp-snapshot/README.md

@@ -37,7 +37,7 @@ defineAcpSnapshotSuite({
 
 A scenario booting a differently-composed tree sets its own `configPath` (an overlay whose basename still ends in `cordis.yml`, so the bin's replay swap finds the sibling `*cordis.snapshot.yml`) and, when that composition changes the request header, its own `headerClass` with its own pinning scenario — the acp-agent example's Code Mode and filesystem scenarios are templates. Each pinning directory stores the normalized full prompt sequence in generated `system-prompt.golden.md` and the corresponding full tool-schema sequence in generated `tool-schemas.golden.json`; `session.jsonl` stores `"system":"{{system}}","tools":"{{tools}}"` while retaining config, reason, and any model-visible prefix. A pin with legitimate mid-run header changes declares `expectedHeaderChanges`, which fixes the length of both sidecar sequences.
 
-Every scenario compares `stdout.golden.jsonl` with cwd-rooted separators canonicalized to `/`. A scenario may set `pinsNativeWindowsStdout` to add a Windows-only comparison against the complete `stdout.golden.windows.jsonl`; the shared golden still runs first on Windows, and the fixture guard requires the sidecar exactly when declared.
+Every scenario compares `stdout.golden.jsonl` with cwd-rooted separators canonicalized to `/`. On Windows, `pinsNativeWindowsStdout` additionally compares the complete `stdout.golden.windows.jsonl` after the shared golden and requires that sidecar exactly when enabled.
 
 Examples use a `cordis.snapshot.yml` overlay with [`dsh-llm-replay`](../llm-replay/README.md). Recording calls the live model and updates model fixtures; keyless refresh replays those fixtures and updates derived stdout, session-log, prompt, and tool-schema snapshots. See the [snapshot RFC](../../../docs/rfc/implemented/testing/2026-06-19-acp-snapshot-tests.md).
 

scripts/AGENTS.md

@@ -1,3 +1,3 @@
 # AGENTS.md — Repository scripts
 
-Gate-related scripts follow the [CI gate rules](../.github/AGENTS.md).
+Gate scripts invoke pnpm shell-free, normalize repository-relative glob paths to `/` at ingestion, and keep platform adaptation at the owning gate boundary instead of a shared platform layer.