@@ -117,7 +117,7 @@ Rules:
 
 ## Current Version/Date
 
-- Project Instructions Version: 2026.06.28.019
+- Project Instructions Version: 2026.06.28.020
 - Date: 2026-06-28
 - Owner: OWNER
 
 
@@ -1,6 +1,6 @@
 # Project Instructions Version
 
-Current Project Instructions Version: 2026.06.28.019
+Current Project Instructions Version: 2026.06.28.020
 
 Last Updated: 2026-06-28
 
@@ -27,6 +27,7 @@ Last Updated: 2026-06-28
 - Removed the local demo `.gfsp` artifact and recorded a file-by-file `src/` destination audit for future scoped migrations.
 - Moved PR017-audited browser/www-owned legacy `src/` files into `www/src/` while preserving public `/src/...` browser route compatibility under the `www` web root.
 - Moved PR019a-audited active browser/runtime shared contracts and tool schemas into `www/src/shared/` while preserving public `/src/shared/...` browser route compatibility.
+- Removed obsolete root `src/` legacy placeholders, stale schema README files, and archived-only debug helpers while preserving active contracts and validation schemas.
 - Codex must read this version file and the latest repository copy of `PROJECT_INSTRUCTIONS.md` before performing work.
 - Codex must discard previously remembered Project Instructions and treat the repository copy as authoritative.
 - Codex must validate canonical report and ZIP paths, branching model, and legacy path avoidance before work proceeds.
@@ -1,7 +1,7 @@
 # Project State
 
 ```yaml
-project_state_version: "2026.06.28.019"
+project_state_version: "2026.06.28.020"
 last_updated: "2026-06-28"
 current_main_commit: "40de767476d70cadfd1292c916844c2f31b6f185"
 repository_status:
@@ -10,18 +10,18 @@ repository_status:
   runtime_database: "Postgres"
   creator_metadata: "API to Postgres"
   creator_assets: "API to R2"
-project_instructions_version: "2026.06.28.019"
-repository_structure_version: "2026.06.28.019"
-canonical_layout_version: "2026.06.28.019"
+project_instructions_version: "2026.06.28.020"
+repository_structure_version: "2026.06.28.020"
+canonical_layout_version: "2026.06.28.020"
 active_teams:
   - "Owner"
   - "Alfa"
   - "Bravo"
   - "Charlie"
   - "Delta"
   - "Golf"
-latest_owner_pr: "PR_26180_OWNER_019b-move-browser-shared-schemas-to-www"
-latest_structure_pr: "PR_26180_OWNER_019b-move-browser-shared-schemas-to-www"
+latest_owner_pr: "PR_26180_OWNER_020-src-legacy-teardown"
+latest_structure_pr: "PR_26180_OWNER_020-src-legacy-teardown"
 valid_top_level_folders:
   - "api/"
   - "deploy/"
@@ -41,7 +41,6 @@ valid_dev_folders:
   - "dev/workspace/"
 known_technical_debt:
   - "Remaining API/server-owned contracts, validation-only schemas, and project data store modules remain under src/shared/ until scoped follow-up PRs move them to api/ or dev/."
-  - "Developer/source reference files remain under src/ until PR_26180_OWNER_020 moves them to dev/."
-  - "src/dev-runtime/admin/.gitkeep remains as a placeholder until PR_26180_OWNER_021 retires the empty root src folder."
+  - "Remaining actively validated contracts, validation schemas, and project data store modules remain under src/shared/ until scoped follow-up PRs move them to api/ or dev/."
   - "repository_directory_standard.md and codex_project_instructions_startup.md are superseded pointers retained for compatibility."
 ```
@@ -40,7 +40,7 @@ The backlog is the authoritative source for determining the next logical PRs.
 - Product Area: Repository Architecture Simplification
 - Status: Active
 - Percent Complete: 99%
-- Active PR: PR_26180_OWNER_019b-move-browser-shared-schemas-to-www
+- Active PR: PR_26180_OWNER_020-src-legacy-teardown
 - Next Milestone: Move remaining API/server-owned source to api/
 - Source / Reference: `dev/build/ProjectInstructions/repository/repository_layout_architecture_plan.md`; `dev/build/ProjectInstructions/repository/www_migration_map.md`
 
 
@@ -90,7 +90,6 @@ Legacy transition buckets:
 - src/shared/contracts/
 - src/shared/schemas/
 - src/shared/projectDataStore/
-- src/dev-runtime/admin/.gitkeep
 
 The `www/src/` legacy transition buckets preserve public `/src/...` browser import compatibility during source retirement. Remaining root `src/` buckets may remain only until explicit stacked migration PRs move them to `api/` or `dev/`.
 
 
@@ -0,0 +1,13 @@
+# PR_26180_OWNER_020 Branch Validation
+
+| Check | Status | Notes |
+|-------|--------|-------|
+| Current branch | PASS | `PR_26180_OWNER_020-src-legacy-teardown` |
+| Expected base | PASS | Stacked on `PR_26180_OWNER_019b-move-browser-shared-schemas-to-www` workstream branch. |
+| Worktree scope | PASS | Changes limited to obsolete root `src/` deletions, Project Instructions/backlog status updates, guard baseline alignment, and PR reports. |
+| Runtime/API/UI/database changes | PASS | No active runtime, API, UI, or database implementation files changed. |
+| Protected dev workspace paths | PASS | No protected `dev/workspace/generated`, `dev/workspace/zips`, or `dev/workspace/tmp` files moved or deleted. |
+
+## Branch Decision
+
+PASS. Branch is valid for the stacked Owner Repository Architecture Simplification workstream.
@@ -0,0 +1,19 @@
+# PR_26180_OWNER_020 Manual Validation Notes
+
+## Manual Review
+
+- Confirmed current branch is `PR_26180_OWNER_020-src-legacy-teardown`.
+- Confirmed deleted files are limited to obsolete root `src/` placeholders, README notes, and debug helpers with no active references.
+- Confirmed remaining root `src/shared/contracts/**`, `src/shared/projectDataStore/**`, and active schema files are still needed by current validation/test references and were not removed.
+- Confirmed archive-only v1-v2 references to deleted debug helpers remain historical and are not active runtime blockers.
+- Confirmed the shared extraction guard baseline change removes only the deleted `src/shared/debug/network.js` entry.
+
+## Manual Runtime Notes
+
+No runtime/UI/API/database behavior was changed. Playwright was not required because this PR removes unreferenced legacy source files and documentation placeholders only.
+
+## ZIP Notes
+
+The repo-structured ZIP for this PR is generated under:
+
+`dev/workspace/zips/PR_26180_OWNER_020-src-legacy-teardown_delta.zip`
@@ -0,0 +1,56 @@
+# PR_26180_OWNER_020-src-legacy-teardown Report
+
+## Executive Summary
+
+PR_26180_OWNER_020 continues the root `src/` retirement work by removing legacy files that no longer have active runtime, API, dev script, validation, or test references. The PR preserves active root `src/shared/contracts/**`, `src/shared/projectDataStore/**`, and active schema files because they are still used by current dev validation/tests and require separate follow-up ownership moves.
+
+No browser, API, database, or product behavior changes are introduced.
+
+## Source Of Truth
+
+- Base branch: `PR_26180_OWNER_019b-move-browser-shared-schemas-to-www`
+- Workstream: Repository Architecture Simplification
+- Audit source: PR017 src destination audit and PR019a contracts/schemas obsolescence audit
+- Project Instructions version updated to `2026.06.28.020`
+
+## Deleted Legacy Files
+
+| File | Decision | Reason |
+|------|----------|--------|
+| `src/dev-runtime/admin/.gitkeep` | Deleted | Obsolete placeholder. Admin compatibility runtime now lives under `www/src/dev-runtime/admin/`. |
+| `src/engine/README.md` | Deleted | Legacy empty-engine-era note, not an active architecture source. |
+| `src/shared/debug/config.js` | Deleted | Old debug helper referenced only by archived v1-v2 material. No active runtime/test/script references. |
+| `src/shared/debug/network.js` | Deleted | Old debug helper referenced only by archived v1-v2 material. No active runtime/test/script references. |
+| `src/shared/debug/noopDevConsoleIntegration.js` | Deleted | Old debug helper referenced only by archived v1-v2 material. No active runtime/test/script references. |
+| `src/shared/schemas/README.md` | Deleted | Legacy schema README superseded by active Project Instructions/governance. |
+| `src/shared/schemas/tools/README.md` | Deleted | Legacy tool schema README superseded by active Project Instructions/governance. |
+
+## Preserved Root src Files
+
+| Path | Decision | Reason |
+|------|----------|--------|
+| `src/shared/contracts/**` | Preserved | Still actively imported by `dev/tests/shared/**` contract validation. |
+| `src/shared/projectDataStore/**` | Preserved | Still actively imported by current project data store validation tests. |
+| `src/shared/schemas/game.manifest.schema.json` | Preserved | Still actively referenced by current validation/tests. |
+| `src/shared/schemas/samples/sample.tool-payload.schema.json` | Preserved | Still actively referenced by current validation/tests. |
+
+## Legacy Pattern Audit
+
+| Pattern | Result |
+|---------|--------|
+| `src/shared/debug/*` active references | PASS: no active references outside archive/report/workspace folders. |
+| `src/engine/README` active references | PASS: no active references outside archive/report/workspace folders. |
+| `src/shared/schemas/README` active references | PASS: no active references outside archive/report/workspace folders. |
+| `src/dev-runtime/admin/.gitkeep` active references | PASS: no active references outside archive/report/workspace folders. |
+| `www/src/tools/**` | Not present in this PR scope. |
+| Protected dev workspace paths | PASS: no protected `dev/workspace/generated`, `zips`, or `tmp` files moved. |
+
+Archive-only v1-v2 references to the removed debug helpers remain under `dev/archive/v1-v2/**`. They are historical reference material, not active runtime or validation dependencies.
+
+## Shared Extraction Guard
+
+`dev/tools/toolbox-dev/checkSharedExtractionGuard.baseline.json` was updated by removing the single baseline entry for deleted file `src/shared/debug/network.js`. No broad baseline regeneration was committed.
+
+## Owner Recommendation
+
+Proceed with this teardown PR. Remaining root `src/` files require follow-up PRs because active validation currently depends on them.
@@ -0,0 +1,19 @@
+# PR_26180_OWNER_020 Requirement Checklist
+
+| Requirement | Status | Evidence |
+|-------------|--------|----------|
+| Base from `PR_26180_OWNER_019b-move-browser-shared-schemas-to-www` | PASS | Branch `PR_26180_OWNER_020-src-legacy-teardown` was created from the PR019b stack. |
+| Do not copy files again | PASS | PR deletes obsolete legacy files only; no duplicate copies were added. |
+| Delete/archive obsolete root `src/` files only after replacement or proof of legacy status | PASS | Seven files removed after active-reference scan found no active runtime/script/test dependencies. |
+| Preserve runtime behavior | PASS | Removed files had no active references outside archive/report/workspace paths. |
+| Hard stop if active `www/api/dev` runtime or validation imports removed files | PASS | Active-reference scan found no active imports for removed files. |
+| Preserve active root `src/shared/contracts/**` and schemas still needed by validation | PASS | Active contract/schema/project data store files remain in root `src/` for follow-up PRs. |
+| Remove `src/dev-runtime/admin/.gitkeep` if obsolete | PASS | Obsolete placeholder removed. |
+| Audit legacy debug/schema/readme patterns | PASS | Active-reference scan completed; archive-only historical references documented. |
+| Do not move protected developer workspace files | PASS | No `dev/workspace/generated`, `dev/workspace/zips`, or `dev/workspace/tmp` files moved. |
+| Required reports under `dev/reports/` | PASS | PR-specific report, checklist, validation report, manual notes, branch validation, diff, and changed-file report created. |
+| Required ZIP under `dev/workspace/zips/` | PASS | Repo-structured ZIP generated for the PR outcome. |
+
+## Remaining Follow-Up
+
+Root `src/shared/contracts/**`, `src/shared/projectDataStore/**`, and active schema files remain because they are still required by current validation/test lanes.
@@ -0,0 +1,33 @@
+# PR_26180_OWNER_020 Validation Report
+
+## Validation Commands
+
+| Command | Status | Notes |
+|---------|--------|-------|
+| `git diff --check` | PASS | No whitespace errors. |
+| `npm run validate:canonical-structure` | PASS | Canonical repository structure guardrail passed with 0 blocking violations. |
+| `node ./dev/scripts/run-node-test-files.mjs dev/tests/dev-runtime/AdminNotesBoundary.test.mjs dev/tests/dev-runtime/StaticWebRootCompatibility.test.mjs dev/tests/tools/ToolManifestBoundary.test.mjs` | PASS | 3/3 targeted node test files passed. |
+| `node dev/tools/toolbox-dev/checkSharedExtractionGuard.mjs` | PASS | Baseline aligned after removing the deleted `src/shared/debug/network.js` entry. |
+| Active legacy reference scan | PASS | No active references to deleted paths found outside archive/report/workspace folders. |
+
+## Active Legacy Reference Scan
+
+Command:
+
+```powershell
+rg -n "src/shared/debug/(config|network|noopDevConsoleIntegration)|src/engine/README|src/shared/schemas/README|src/shared/schemas/tools/README|src/dev-runtime/admin/.gitkeep" www api dev/scripts dev/tests dev/tools package.json .github --glob '!dev/archive/**' --glob '!dev/reports/**' --glob '!dev/workspace/**'
+```
+
+Result: no matches.
+
+## Archive References
+
+Historical references remain under `dev/archive/v1-v2/**`. These are intentionally excluded from active validation blockers because `dev/archive/` is historical reference material only.
+
+## Product Impact
+
+- Runtime behavior changed: No
+- UI changed: No
+- API changed: No
+- Database changed: No
+- Product feature changed: No