enhance(#4221): replace installer Read() deny rules with a managed secret-read guard hook (#4236)

* feat(#4221): gsd-secret-read-guard PreToolUse hook + registration

Add hooks/gsd-secret-read-guard.js, a blocking PreToolUse guard on
Read|Grep|Bash that denies reads of .env, .env.<suffix> and .secrets
(the .env.example/.sample/.template/.dist templates stay readable).
Read checks file_path; Grep checks an explicit path and judges the glob
per brace alternative; Bash runs a two-pass token scan (quotes, comments,
redirects with fd digits, separators, $( )/backtick/<( ) recursion,
heredoc bodies never scanned as commands, nested bash -c/eval rescans,
git <ref>:<path> shapes) with a closed non-reading exemption set for
existence checks. Fail-open crash policy; 1 MiB commands are denied as
command-too-large; more than 64 glob alternatives as glob-too-complex.

Why: Claude Code 2.1.259 makes every `cd DIR && grep …` compound prompt
for approval whenever any Read() deny rule exists, even in auto mode. A
hook denial is not a permission rule and never arms that check. The
installer-written deny rules are retired in the follow-up commit.

Registration: hooks.json (Read|Grep|Bash, timeout 5), build-hooks
HOOKS_TO_COPY, managed-hooks-registry, runtime-hooks-surface (blocking
guard with BLOCKING_GUARD_TIMEOUT_S; Kimi ReadFile|Grep|Shell),
shell-command-projection managed sets, installer-migration-report,
OpenCode/Kilo plugin (grep tool mapping, include -> glob, dispatch),
docs tables in five locales, ADR-766 always-on list, regen:derived
fixtures, and a new table-driven unit suite.

* test(#4221): pin the secret-read guard in existing hook gates

Register gsd-secret-read-guard.js in every existing hook gate: the
hooks-crash-policy table (deny row; 6 -> 7 deny cases), plugin-manifest
REQUIRED_HOOKS and its Read|Grep|Bash group, docs-hooks-table-parity
EXPECTED_SURFACE_HOOKS, install.test MANAGED_JS_HOOKS, install-minimal-
hooks JS_HOOKS/BLOCKING_GUARDS, portable-node-runner GUARD_HOOKS,
kilo-upgrades PLUGIN_GUARD_HOOKS, the Kimi normalization-parity and
typed-payload floors, the OpenCode adapter (grep mapping, include ->
glob, three dispatch tests) and a Kimi TOML matcher assertion.

* fix(#4221): retire installer Read() deny rules (legacy filter)

Rename GSD_CLAUDE_DENY_PERMISSIONS to GSD_CLAUDE_LEGACY_DENY_PERMISSIONS
and stop adding the three Read(.env) / Read(.env.*) / Read(.secrets)
strings. mergeClaudePermissions now only filters them out of an existing
permissions.deny: an absent deny key stays absent, a malformed one is
still repaired to [], and an array emptied by the filter is deleted so
no `"deny": []` residue is left. Uninstall filters the same legacy list
and, symmetric with the Antigravity branch, drops an emptied allow or
deny key and an emptied permissions object.

Unlike the #2278 allow-side migration there is no surviving current
deny list, so the constant is renamed rather than mirrored. Removal is
byte-exact: a hand-written identical rule is indistinguishable from the
installer's and is removed too (the manifest never recorded permission
strings). USER-GUIDE and CONTEXT.md updated.

* test(#4221): flip install-regressions deny-rule assertions to the retired shape

The fresh-merge, non-destructive merge, idempotency, end-to-end install,
reinstall and uninstall assertions now expect no Read(.env*) deny rules
and no permissions.deny key on a fresh install; the deny:null repair case
is kept. A new describe block covers the legacy filter: retired strings
removed with a user entry kept, partial sets, near-miss strings
untouched, idempotency, GSD-only deny array deleted, a pre-existing
empty deny preserved, and uninstall symmetry for allow/deny/permissions.

* chore(#4221): add changeset fragment for PR #4236

* fix(#4221): case-fold names; scan shell stdin and xargs pipes

Review round 1 (trek-e):

- Blocker: secret-name matching is now case-insensitive in the Read,
  Grep (path and glob) and Bash paths, so `.ENV` / `.Secrets` on a
  case-insensitive filesystem are recognized as the same secret file.
- Major: a shell interpreter's script is now scanned wherever it comes
  from. The tokenizer keeps heredoc bodies as per-segment tokens and
  records separator operators; pass 2 groups by segment id and resolves
  bash/sh/zsh/dash/ksh/su invocation mode: `-c` (including combined
  `-lc`) scans the script operand, a file operand is checked as a file
  (a `<( )` operand's echo/printf output is reconstructed), otherwise
  stdin is the script and heredocs, here-strings and a piped echo/printf
  source are scanned. `eval` joins all its operands; `source`/`.` handle
  process substitution. Data heredocs (`cat <<EOF`, the commit-message
  shape) stay unscanned.
- Major: `… | xargs <cmd>` checks the upstream segment's operands as
  file names when the sub-command reads (`echo .env | xargs cat`,
  `find . -name .env | xargs cat`); `-a`/`--arg-file` suppresses the
  inference; a shell sub-command's `-c` script is scanned.

Header, USER-GUIDE bullet and changeset updated; documented gaps now
include piped scripts from non-echo sources and `exec`/`timeout`
wrappers. 60 new suite cases pin the block and allow shapes.

---------

Co-authored-by: Tom Boucher <trekkie@nomorestars.com>

docs/adr/766-claude-code-plugin-manifest-module.md

@@ -30,7 +30,7 @@ The mapping is **defined, not incidental**:
 | Agent surface (`agents/*.md`) | *(omitted — default `agents/` discovery)* | the explicit `agents: <string>` form is rejected by the plugin schema; relying on Claude Code's default `agents/` discovery loads them and stays self-maintaining. Agents are already plugin-safe — their `hooks`/`permissionMode` frontmatter is inert. |
 | Always-on hook policy (subset of the Installer Module's `settings.json` wiring) | `hooks: "./hooks/hooks.json"` | see below. |
 
-The hook projection is the load-bearing part of this Module, because of the external constraint: a plugin's agents cannot carry hook frontmatter, so **all plugin-path hook wiring must live in `hooks/hooks.json`**. The Module projects *only the always-on subset* of the Installer Module's Claude hook wiring — `gsd-check-update` (SessionStart), `gsd-context-monitor` (PostToolUse), and the security guards `gsd-prompt-guard` / `gsd-read-guard` / `gsd-worktree-path-guard` / `gsd-read-injection-scanner` / `gsd-write-guard` (PreToolUse, #2255) — preserving each event, matcher, and timeout. The installer's **config-gated opt-in** hooks (workflow-guard, validate-commit, graphify-update, session-state, phase-boundary, update-banner) are deliberately excluded: a static manifest cannot read a project's `.planning/config.json` to honor those gates, so projecting them would run them unconditionally — a behavior change the Module must not introduce. Hook commands reference bundled scripts through Claude Code's `${CLAUDE_PLUGIN_ROOT}` variable.
+The hook projection is the load-bearing part of this Module, because of the external constraint: a plugin's agents cannot carry hook frontmatter, so **all plugin-path hook wiring must live in `hooks/hooks.json`**. The Module projects *only the always-on subset* of the Installer Module's Claude hook wiring — `gsd-check-update` (SessionStart), `gsd-context-monitor` (PostToolUse), and the security guards `gsd-prompt-guard` / `gsd-read-guard` / `gsd-worktree-path-guard` / `gsd-read-injection-scanner` / `gsd-write-guard` (PreToolUse, #2255) / `gsd-secret-read-guard` (PreToolUse `Read|Grep|Bash`, #4221) — preserving each event, matcher, and timeout. The installer's **config-gated opt-in** hooks (workflow-guard, validate-commit, graphify-update, session-state, phase-boundary, update-banner) are deliberately excluded: a static manifest cannot read a project's `.planning/config.json` to honor those gates, so projecting them would run them unconditionally — a behavior change the Module must not introduce. Hook commands reference bundled scripts through Claude Code's `${CLAUDE_PLUGIN_ROOT}` variable.
 
 The interface of this Module is therefore a **conformance contract**, validated two ways: `claude plugin validate --strict` (the external tool's view) and an in-repo drift-guard test (`tests/plugin-manifest.test.cjs`) that locks the identity mapping, the version sync, the always-on hook contract, and the absence of opt-in hooks. Manifest component paths are resolved relative to the **plugin root** (the directory containing `.claude-plugin/`), which is the repository root.