'Oracle-to-PostgreSQL Migration Expert' Custom Agent: Update Custom Agent & Plugin & Skills (#2566)

* Enhance Oracle-to-PostgreSQL migration skills and documentation

- Update migration agent guidelines to prioritize extension tool usage for code migration.
- Refine migration phases with detailed steps for pre-migration review and schema migration.
- Add new reviewing skill references for PostgreSQL materialized view refresh and UNION ALL planner risks.
- Ensure consistency in collation handling and testing strategies across skills.

* - Review migration phases to ensure correct order of execution
- Add exit criteria to each migration phase
- Remove invocation of `ms-ossdata.vscode-pgsql` extension due to dependency on VSCode
- Update README.md to reflect changes in migration phases and exit criteria
- Update broken reference to custom agent in plugin.json

* Enhance downstream migration skills and following custom agent improvements

- Added new skill for migrating .NET data access code from Oracle to PostgreSQL.
- Updated README to include new migration skill.
- Improved existing skills with clearer file naming conventions and migration actions.
- Added reference documents for handling Oracle-specific functions and pagination.
- Created detailed guides for NVL, DECODE, ROWNUM, SYSDATE, and DUAL replacements.

* Clarify PostgreSQL schema immutability and stored procedure migration risks

* Update target schema path in migration documentation for clarity

* fix(skills): clarify Phase 3-only scope for Oracle test skills

Both Oracle test skills were ambiguously worded in ways that could
cause a model to invoke them during Phase 6 (PostgreSQL test migration)
instead of using them exclusively in Phase 3.

Key changes:
- Rewrite descriptions to explicitly state Phase 3-only usage and
  warn against invoking during Phase 6
- Replace "scaffold for Oracle first" with "Oracle only" to remove
  the false implication of a second PostgreSQL scaffolding step
- Replace "Tests validate behavior consistency when running against
  Oracle or PostgreSQL" with clear Oracle-only framing
- Rename "DB-agnostic assertions" → "Assertion portability" and
  explain the why (survive Phase 6 migration without rewrites)
- Fix datetime bullet in integration tests skill to use generic
  Oracle column precision language instead of PostgreSQL type syntax
- Name Oracle NuGet package explicitly (Oracle.ManagedDataAccess.Core)

* feat(oracle-to-postgres): gate Phase 1 on DDL presence; add DDL scan to Phase 2 risk analysis

- Phase 1 success criteria now requires Oracle DDL artifacts to be
  confirmed present at the recorded location before proceeding.
  If missing, the agent stops and prompts the user to provide them.

- Phase 2 risk analysis now explicitly scans DDL/Oracle/{ProjectName}/
  as supplemental context, summarising procedure complexity indicators
  (dynamic SQL, DBMS_* / UTL_* references, autonomous transactions,
  pipelined functions, BULK COLLECT/FORALL, REF CURSOR, TYPE bodies)
  rather than ingesting DDL files wholesale. This ensures schema-level
  migration risk is captured even when it isn't visible in application
  code alone.

* - Merge in latest 'main' changes
- Update custom agent plugin (eg resolve conflict and add new skill)
- Validate skills
- Run build

* chore(plugin.json): update version to 1.1.0

* feat(oracle-to-postgres): update version to 1.1.0 for migration expert plugin

* fix: add INOUT to ignore-words-list for PostgreSQL migration

---------

Co-authored-by: TCPrimedPaul <paul.delannoy@tc.gc.ca>

skills/reviewing-oracle-to-postgres-migration/references/oracle-rownum-pagination.md

@@ -0,0 +1,75 @@
+# Oracle to PostgreSQL: ROWNUM Pagination vs LIMIT/OFFSET
+
+## Problem
+
+Oracle uses `ROWNUM` pseudo-column for pagination and row-limiting. PostgreSQL uses standard `LIMIT` / `OFFSET` syntax. `ROWNUM` is also fundamentally different in *when* it is assigned, which affects filtering behavior.
+
+## Behavior Comparison
+
+**Oracle:**
+- `ROWNUM` is assigned before `ORDER BY` — filtering with `ROWNUM` on an unordered result set is non-deterministic
+- Common pattern to get "top N ordered rows" requires a subquery:
+  ```sql
+  SELECT * FROM (SELECT * FROM t ORDER BY col) WHERE ROWNUM <= 10
+  ```
+- `ROWNUM BETWEEN n AND m` requires a double-wrapped subquery
+
+**PostgreSQL:**
+- `LIMIT n` restricts result rows after `ORDER BY` is applied — straightforward and deterministic
+- `OFFSET n` skips rows; combine with `LIMIT` for pagination
+- No `ROWNUM` pseudo-column exists
+
+## Code Example
+
+```sql
+-- Oracle: top 10 rows by date
+SELECT * FROM (
+  SELECT * FROM orders ORDER BY created_at DESC
+) WHERE ROWNUM <= 10;
+
+-- PostgreSQL equivalent
+SELECT * FROM orders ORDER BY created_at DESC LIMIT 10;
+
+-- Oracle: rows 11–20 (keyset pagination via ROWNUM)
+SELECT * FROM (
+  SELECT t.*, ROWNUM rn FROM (
+    SELECT * FROM orders ORDER BY created_at DESC
+  ) t WHERE ROWNUM <= 20
+) WHERE rn > 10;
+
+-- PostgreSQL equivalent
+SELECT * FROM orders ORDER BY created_at DESC LIMIT 10 OFFSET 10;
+```
+
+## Migration Actions
+
+### 1. Stored Procedures
+
+Replace all `ROWNUM`-based limiting patterns with `LIMIT`/`OFFSET`:
+
+```sql
+-- Oracle
+WHERE ROWNUM = 1
+WHERE ROWNUM <= :n
+
+-- PostgreSQL
+LIMIT 1
+LIMIT :n            -- note: use $n parameter style in PL/pgSQL
+```
+
+For subquery wrapping patterns:
+```sql
+-- Oracle
+SELECT * FROM (SELECT ... ORDER BY col) WHERE ROWNUM <= :n
+
+-- PostgreSQL
+SELECT ... ORDER BY col LIMIT :n
+```
+
+### 2. Application Code (inline SQL strings)
+
+Search for `ROWNUM` in C# string literals, `StringBuilder`, and query-builder methods. Apply the same replacement patterns above.
+
+### 3. Tests
+
+Ensure integration tests validate that result set sizes are correct and that ordering is preserved (i.e., the correct *n* rows are returned, not just any *n* rows).