grok: fix xsearch (multi-agent web_search), pin grok-build, RTFM doc sweep

Root-caused the long-standing `ask-grok.sh xsearch` "no result (stopReason=)"
failure by reading Grok's bundled docs (~/.grok/docs/user-guide + README) instead
of probing:
- web_search runs a SEPARATE multi-agent model (grok-4.20-multi-agent), so the
  wrapper's blanket --no-subagents strangled it -> indefinite hang, 0 bytes. Scoped
  --no-subagents OFF xsearch; use --yolo (documented headless tool-run posture).
- xsearch prompt mandated X/Twitter search on every call (slow multi-agent) and the
  budget was 240s -> still timed out. Now web-primary (X only when relevant), 300s.
  Validated end-to-end through the wrapper: 23s, correct answer + 3 sources.

Model: pin -m grok-build (xAI flagship, 512k, the documented default) for the
reasoning modes (text/verify/review*) so quality is deterministic and not at the
mercy of the runtime default (this machine drifted to grok-composer-2.5-fast, a fast
Cursor coding model). xsearch + image/video keep the runtime default. Validated text
mode on grok-build (13s).

Doc accuracy (SKILL.md): corrected the model facts (default, the separate web_search
model, --effort unsupported on grok-build per supports_reasoning_effort:false);
documented the xsearch subagent exception. Fixed a stale in-script comment claiming
--rules/--disallowed-tools "tripped the CLI" (both are valid headless flags).

memory: add feedback_interview_ai_read_docs (read bundled docs / interview the model
before probing) + index; errorlog correction.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/skills/grok/SKILL.md

@@ -91,10 +91,10 @@ Grok is **per-machine** — the skill syncs fleet-wide but the binary does not.
 
 ## Safety / operational notes
 
-- `~/.grok/config.toml` defaults to `permission_mode = "always-approve"` (auto-runs tools). The wrapper overrides with `--permission-mode dontAsk` and `--no-subagents`; do not bypass that.
+- `~/.grok/config.toml` defaults to `permission_mode = "always-approve"` (auto-runs tools). The wrapper's single-context modes (`text`/`verify`/`review*`) override with `--permission-mode dontAsk --no-subagents` (cheap, bounded, timeout-predictable). **`xsearch` is the deliberate exception:** it uses `--yolo` and leaves subagents ENABLED, because `web_search` runs the `grok-4.20-multi-agent` model — passing `--no-subagents` made it hang with zero output (the long-standing xsearch-empty bug; root-caused + fixed 2026-06-16). Don't re-add `--no-subagents` to xsearch.
 - Prompts are passed via `--prompt-file` only (inline args break on shell quoting).
-- `grok-build` rejects `--effort`/`--reasoning-effort` (400) — don't pass them.
-- Models available: `grok-build` (default), `grok-composer-2.5-fast`. The agent self-reports as Grok 4.3.
+- `grok-build` does NOT support `--effort`/`--reasoning-effort` (`supports_reasoning_effort:false` in the model info) — passing them 400s. Don't.
+- Models (verify live with `grok models`): `grok-build` ("Grok Build", xAI's latest coding model, 512k ctx — the **documented** default per `docs/user-guide/11-custom-models.md`) and `grok-composer-2.5-fast` ("Cursor's latest coding model", fast). **Gotcha:** on this machine the runtime default that `grok models` reports is `grok-composer-2.5-fast`, and the wrapper pins no `-m`, so it currently rides whatever the runtime default is (not necessarily grok-build). `web_search` uses a SEPARATE model, `grok-4.20-multi-agent` (set via `[tools] web_search` / `GROK_WEB_SEARCH_MODEL`).
 - After media gen, Claude should **view the image** (Read tool) to confirm correctness; videos can be confirmed by header/ffprobe.
 
 ## Reference