Centralize Postgres connection string policy across all modules

Extract connection string building into PostgresConnectionStringPolicy so all
services use consistent pooling, application_name, and timeout settings.
Adopt the new policy in 20+ module DataSource/ServiceCollectionExtensions classes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/__Libraries/StellaOps.Infrastructure.Postgres/AGENTS.md

@@ -19,6 +19,8 @@
 ## Determinism & Guardrails
 - Target runtime: .NET 10, Npgsql 9.x; keep options defaults deterministic (UTC timezone, statement timeout, stable pagination ordering).
 - Tenant context must be set via `set_config('app.current_tenant', ...)` on every connection before use; never bypass DataSourceBase.
+- Runtime `NpgsqlDataSource` creation must carry a stable `application_name`; prefer `PostgresConnectionStringPolicy` or an explicit `NpgsqlConnectionStringBuilder.ApplicationName`.
+- Anonymous `NpgsqlDataSource.Create(...)` is forbidden in steady-state runtime code. Allow exceptions only for tests, migrations, CLI/setup paths, or sprint-documented one-shot diagnostics.
 - Migrations ship as embedded resources; MigrationRunner uses SHA256 checksums and `RunFromAssemblyAsync`???do not execute ad-hoc SQL outside tracked migrations.
 - Respect air-gap posture: no external downloads at runtime; pin Postgres/Testcontainers images (`postgres:16-alpine` or later) in tests.
 
@@ -30,4 +32,3 @@
 ## Handoff Notes
 - Align configuration defaults with the provisioning values under `devops/database/postgres` (ports, pool sizes, SSL/TLS).
 - Update this AGENTS file whenever connection/session rules or provisioning defaults change; record updates in the sprint Execution Log.
-

src/__Libraries/StellaOps.Infrastructure.Postgres/Connections/DataSourceBase.cs

@@ -241,15 +241,8 @@ public abstract class DataSourceBase : IAsyncDisposable
         return connection;
     }
 
-    private static string BuildConnectionString(PostgresOptions options)
-    {
-        var builder = new NpgsqlConnectionStringBuilder(options.ConnectionString)
-        {
-            Pooling = options.Pooling,
-            MaxPoolSize = options.MaxPoolSize,
-            MinPoolSize = options.MinPoolSize
-        };
-
-        return builder.ToString();
-    }
+    private string BuildConnectionString(PostgresOptions options)
+        => PostgresConnectionStringPolicy.Build(
+            options,
+            PostgresConnectionStringPolicy.BuildDefaultApplicationName(ModuleName));
 }

src/__Libraries/StellaOps.Infrastructure.Postgres/Connections/PostgresConnectionStringPolicy.cs

@@ -0,0 +1,103 @@
+using Npgsql;
+using StellaOps.Infrastructure.Postgres.Options;
+
+namespace StellaOps.Infrastructure.Postgres.Connections;
+
+/// <summary>
+/// Applies StellaOps runtime defaults to PostgreSQL connection strings.
+/// </summary>
+public static class PostgresConnectionStringPolicy
+{
+    public static string Build(PostgresOptions options, string defaultApplicationName)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        ArgumentException.ThrowIfNullOrWhiteSpace(defaultApplicationName);
+
+        return Build(
+            options.ConnectionString,
+            string.IsNullOrWhiteSpace(options.ApplicationName)
+                ? defaultApplicationName.Trim()
+                : options.ApplicationName.Trim(),
+            options.Pooling,
+            options.MinPoolSize,
+            options.MaxPoolSize,
+            options.ConnectionIdleLifetimeSeconds);
+    }
+
+    public static string Build(
+        string connectionString,
+        string applicationName,
+        bool pooling = true,
+        int minPoolSize = 1,
+        int maxPoolSize = 100,
+        int? connectionIdleLifetimeSeconds = null)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(connectionString);
+        ArgumentException.ThrowIfNullOrWhiteSpace(applicationName);
+
+        var normalizedMinPoolSize = Math.Max(minPoolSize, 0);
+        var normalizedMaxPoolSize = Math.Max(maxPoolSize, normalizedMinPoolSize);
+
+        var builder = new NpgsqlConnectionStringBuilder(connectionString)
+        {
+            ApplicationName = applicationName.Trim(),
+            Pooling = pooling,
+            MinPoolSize = normalizedMinPoolSize,
+            MaxPoolSize = normalizedMaxPoolSize,
+        };
+
+        if (connectionIdleLifetimeSeconds.HasValue && connectionIdleLifetimeSeconds.Value > 0)
+        {
+            builder.ConnectionIdleLifetime = connectionIdleLifetimeSeconds.Value;
+        }
+
+        return builder.ToString();
+    }
+
+    public static string BuildDefaultApplicationName(string moduleName)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(moduleName);
+
+        return $"stellaops-{ToKebabCase(moduleName.Trim())}";
+    }
+
+    private static string ToKebabCase(string value)
+    {
+        var chars = new List<char>(value.Length + 8);
+        for (var i = 0; i < value.Length; i++)
+        {
+            var current = value[i];
+            if (char.IsWhiteSpace(current) || current is '_' or '-')
+            {
+                if (chars.Count > 0 && chars[^1] != '-')
+                {
+                    chars.Add('-');
+                }
+
+                continue;
+            }
+
+            if (char.IsUpper(current))
+            {
+                var hasPrevious = chars.Count > 0;
+                var previous = hasPrevious ? value[i - 1] : '\0';
+                var hasNext = i + 1 < value.Length;
+                var next = hasNext ? value[i + 1] : '\0';
+
+                if (hasPrevious
+                    && chars[^1] != '-'
+                    && (!char.IsUpper(previous) || (hasNext && char.IsLower(next))))
+                {
+                    chars.Add('-');
+                }
+
+                chars.Add(char.ToLowerInvariant(current));
+                continue;
+            }
+
+            chars.Add(char.ToLowerInvariant(current));
+        }
+
+        return new string(chars.ToArray()).Trim('-');
+    }
+}

src/__Libraries/StellaOps.Infrastructure.Postgres/Options/PostgresOptions.cs

@@ -20,6 +20,11 @@ public sealed class PostgresOptions
     /// </summary>
     public int MaxPoolSize { get; set; } = 100;
 
+    /// <summary>
+    /// Stable PostgreSQL application name used for runtime attribution.
+    /// </summary>
+    public string? ApplicationName { get; set; }
+
     /// <summary>
     /// Minimum number of connections in the pool. Default is 1.
     /// </summary>

src/__Libraries/StellaOps.Infrastructure.Postgres/TASKS.md

@@ -5,6 +5,7 @@ Source of truth: `docs-archived/implplan/2025-12-29-csproj-audit/SPRINT_20251229
 
 | Task ID | Status | Notes |
 | --- | --- | --- |
+| SPRINT_20260405_011-XPORT-STD | DONE | `docs/implplan/SPRINT_20260405_011___Libraries_transport_pooling_and_attribution_hardening.md`: shared transport hardening, PostgreSQL application-name policy, runtime caller remediation, and static guardrails. |
 | AUDIT-0089-M | DONE | Revalidated 2026-01-08; maintainability audit for Infrastructure.Postgres. |
 | AUDIT-0089-T | DONE | Revalidated 2026-01-08; test coverage audit for Infrastructure.Postgres. |
 | AUDIT-0089-A | TODO | Pending approval (non-test project; revalidated 2026-01-08). |