diff --git a/histdb/README.md b/histdb/README.md
index c0809ed..201db03 100644
--- a/histdb/README.md
+++ b/histdb/README.md
@@ -20,6 +20,7 @@ Read-only reference. There's no code here — these files exist so an LLM can an
 ```text
 histdb/
   README.md                this file
+  connectioninfo.md        Verified Runtime DB connection on this machine (server, sqlcmd recipe, sanity probes)
   01-overview.md           OLE DB provider, linked server, extension tables, four-part / OPENQUERY / OPENROWSET
   02-syntax-limits.md      Supported / unsupported SQL features, joins, sub-SELECTs, time-domain extensions overview
   03-retrieval-modes.md    Every wwRetrievalMode value (Cyclic, Delta, Full, Interpolated, BestFit, Average, Min, Max, Integral, Slope, Counter, ValueState, RoundTrip, Predictive, BoundingValue)
@@ -33,6 +34,7 @@ histdb/
 
 | Task | Go to |
 | --- | --- |
+| Connect from this machine — server, instance, `sqlcmd` recipe, sanity probes | [`connectioninfo.md`](connectioninfo.md) |
 | Connect to Historian via SQL Server, pick a query style (four-part / view / OPENQUERY / OPENROWSET) | [`01-overview.md`](01-overview.md) |
 | What SQL syntax works and what doesn't (LIKE, IN, OR, joins, CONVERT, sub-SELECTs) | [`02-syntax-limits.md`](02-syntax-limits.md) |
 | Pick the right retrieval mode for the question being asked | [`03-retrieval-modes.md`](03-retrieval-modes.md) |
diff --git a/histdb/connectioninfo.md b/histdb/connectioninfo.md
new file mode 100644
index 0000000..f94f700
--- /dev/null
+++ b/histdb/connectioninfo.md
@@ -0,0 +1,87 @@
+# Historian Runtime DB — Connection Information
+
+Verified working state on this machine. Capture date: 2026-05-03.
+
+## Connection parameters
+
+| Parameter       | Value |
+| --- | --- |
+| Server          | `localhost` (default instance, `MSSQLSERVER`) |
+| Database        | `Runtime` |
+| Port            | 1433 (default) |
+| Authentication  | Windows integrated |
+| Account         | `DESKTOP-6JL3KKO\dohertj2` |
+| Server role     | `sysadmin` (full access; AVEVA `aaUsers` / `aaPowerUsers` / `aaAdministrators` group checks short-circuit through sysadmin) |
+| SQL Server      | 2017 Express, 14.0.2105.1 (RTM-GDR, KB5084819) |
+
+## `sqlcmd` recipe
+
+```powershell
+sqlcmd -E -S . -d Runtime -W -Q "<your SELECT>"
+```
+
+- `-E` — Windows authentication.
+- `-S .` — local default instance (equivalent to `localhost`).
+- `-d Runtime` — Historian DB.
+- `-W` — strip trailing whitespace from columns.
+
+For pipe-separated machine-readable output, add `-s "|" -h -1` (the `-h -1` suppresses headers; drop it to keep them):
+
+```powershell
+sqlcmd -E -S . -d Runtime -W -s "|" -Q "..."
+```
+
+## Sanity probes
+
+These four queries together verify "I'm in the right DB and can reach Historian":
+
+```sql
+-- 1. Identify
+SELECT @@SERVERNAME AS server, DB_NAME() AS db, SUSER_SNAME() AS [user];
+
+-- 2. Tag tables exist (numbers will differ — non-zero is the point)
+SELECT 'Tag'         AS tbl, COUNT(*) AS rows_ FROM Tag         UNION ALL
+SELECT 'AnalogTag',         COUNT(*)          FROM AnalogTag    UNION ALL
+SELECT 'DiscreteTag',       COUNT(*)          FROM DiscreteTag  UNION ALL
+SELECT 'StringTag',         COUNT(*)          FROM StringTag;
+
+-- 3. Linked servers (both should return one row)
+SELECT name FROM sys.servers WHERE name IN ('INSQL', 'INSQLD');
+
+-- 4. End-to-end OLE DB pull through INSQL
+SELECT TOP 3 TagName, DateTime, Value
+FROM History
+WHERE TagName = 'SysTimeSec'
+  AND DateTime >= DATEADD(MINUTE, -1, GETDATE())
+  AND DateTime <= GETDATE()
+  AND wwRetrievalMode = 'Cyclic'
+  AND wwCycleCount = 5;
+```
+
+If probe 4 returns rows, the full retrieval path is live.
+
+## Tags actually present (snapshot)
+
+At capture date: 239 total tags (`Tag`), 219 analog, 18 discrete, 1 string. Useful built-ins for smoke-testing without depending on plant data: `SysTimeSec`, `SysTimeMin`, `SysTimeHour`, `SysPulse`, `SysPerfCPUTotal`, `SysSpaceMain`.
+
+## Linked servers
+
+Both auto-installed by Historian. Documented in [`01-overview.md`](01-overview.md#linking-insql-to-sql-server).
+
+| Linked server | Role |
+| --- | --- |
+| `INSQL`  | Primary alias for the Historian OLE DB Provider. Use this in four-part queries (`INSQL.Runtime.dbo.History`) and `OPENQUERY(INSQL, '...')`. |
+| `INSQLD` | Identical alias used to satisfy SQL Server when the same query joins the legacy analog and discrete history tables. |
+
+## Other client paths
+
+- **SSMS / Azure Data Studio** — point at server `.`, Windows auth, database `Runtime`.
+- **PowerShell `Invoke-Sqlcmd`** — needs the `SqlServer` module (this machine has `SQLPS 14.0` only; install `SqlServer` from PSGallery if you want it). Equivalent: `Invoke-Sqlcmd -ServerInstance . -Database Runtime -Query "..."`.
+- **.NET / ODBC / ADO.NET** — connection string `Server=.;Database=Runtime;Integrated Security=SSPI;`.
+- **Python** — `pyodbc.connect("Driver={SQL Server};Server=.;Database=Runtime;Trusted_Connection=yes;")`.
+
+## Caveats
+
+- The tag tables (`Tag`, `AnalogTag`, etc.) are **real SQL Server tables** — fast, normal joins, no `wwXxx` semantics. The history tables (`History`, `Live`, `WideHistory`, `AnalogSummaryHistory`, `StateSummaryHistory`, `Events`, `HistoryBlock`) are **extension tables** served by `INSQL`; they require the patterns in [`01-overview.md`](01-overview.md) and [`02-syntax-limits.md`](02-syntax-limits.md).
+- A `WHERE` clause is mandatory on every extension table except `HistoryBlock`. Probe 4 above demonstrates the minimum acceptable shape (TagName + DateTime range + retrieval mode).
+- `Runtime` and the Galaxy Repository (covered by [`../grdb/`](../grdb/)) are **different** SQL Server databases on the same instance. Don't cross-query.