fix(claude_md): restore full default content (BQ cost guard, hybrid example, ad-hoc table, deeper guidance)

config/claude_md_template.txt

@@ -73,7 +73,7 @@ For local-mode tables, query directly with `da query "SELECT … FROM <table>"`.
 | Pattern | Tool | Use when |
 |---------|------|----------|
 | **`da fetch`** (preferred) | materializes a filtered subset locally → query the snapshot | repeated questions on same slice |
-| **`da query --remote`** | one-shot, server-side execution against BigQuery | single aggregate / cheap probe |
+| **`da query --remote`** | one-shot, server-side execution against BigQuery (works for BASE TABLE rows directly + VIEW/MATERIALIZED_VIEW rows via the BQ jobs API; cost-guarded by a 5 GiB scan cap configurable in /admin/server-config) | single aggregate / cheap probe |
 | **`da query --register-bq`** | hybrid joins between local snapshots and ad-hoc BQ subqueries | crossing local + remote |
 
 ### Permission model + cost — important
@@ -111,7 +111,7 @@ Rules of thumb:
 
 ### Snapshot freshness — when to refresh
 
-Snapshots are point-in-time copies. They go stale as the source data updates. For each new conversation:
+Snapshots are point-in-time copies. They go stale as the source data updates (most BQ tables refresh daily; check `sync_schedule` per `da catalog`). For each new conversation:
 
 ```
 da snapshot list                            # see existing snapshots + their ages
@@ -119,6 +119,26 @@ da snapshot drop my_recent                  # drop stale ones
 da fetch <table> --select ... --where ... --as my_recent   # re-fetch
 ```
 
+If the question is time-sensitive (e.g. "today's orders"), assume any snapshot older than the table's `sync_schedule` is stale and refresh.
+
+### Hybrid query example — local + remote in one query
+
+`da query --register-bq` lets a single SQL statement join a local table with an ad-hoc BQ subquery. The BQ subquery runs first (server-side), result registered as a DuckDB view, then the joined query runs locally.
+
+```
+da query \
+  --register-bq "traffic=SELECT date, country, SUM(views) AS views \
+                 FROM \`prj.web_analytics.sessions\` \
+                 WHERE date >= DATE_SUB(CURRENT_DATE(), INTERVAL 30 DAY) \
+                 GROUP BY 1, 2" \
+  --sql "SELECT o.date, o.country, o.revenue, t.views, o.revenue / NULLIF(t.views,0) AS rev_per_view \
+         FROM orders o \
+         JOIN traffic t ON o.date = t.date AND o.country = t.country \
+         ORDER BY 1 DESC"
+```
+
+The BQ subquery MUST contain `WHERE` and/or `GROUP BY` to keep the registered result manageable (target: under 500K rows, well under 100 MB). Multiple `--register-bq` flags can compose multiple BQ sources. For complex SQL, use `--stdin` mode (`echo '{"register_bq":{...},"sql":"..."}' | da query --stdin`).
+
 ### BigQuery SQL flavor for `--where`
 
 Source-typed `bigquery` tables use BigQuery dialect, not DuckDB:
@@ -130,6 +150,29 @@ Source-typed `bigquery` tables use BigQuery dialect, not DuckDB:
 - Regex: `REGEXP_CONTAINS(col, r'pattern')` (raw string!)
 - Cast: `CAST(x AS INT64)` (NOT `INT`)
 
+### When the table you want isn't in `da catalog`
+
+The table may exist in BigQuery but not be registered with Agnes yet. Two options:
+
+1. **Ad-hoc one-shot** — register a BQ subquery as a view inline, no admin needed
+   if the agnes server SA has BQ access:
+   ```
+   da query --register-bq "live=SELECT * FROM \`project.dataset.table\` WHERE date >= '...' LIMIT 1000" \
+            --sql "SELECT * FROM live"
+   ```
+2. **Ask admin to register** the table with `query_mode: "remote"` so it shows up
+   in `da catalog` and supports `da fetch` / `da query --remote`. This is the
+   right path for any table you'll query repeatedly.
+
+### Deeper guidance
+
+For the full protocol, including hybrid-query examples, snapshot hygiene, and
+when NOT to use `da fetch`, run:
+
+```
+da skills show agnes-data-querying
+```
+
 ## Corporate Memory
 
 Rules injected by `da sync` from the server's corporate knowledge base live in `.claude/rules/km_*.md`. They are automatically loaded by Claude Code on every session start.