Add TESTABILITY GATE and BUILD quality requirement without modifying existing content.

Author: DavidQ

docs/dev/CODEX_COMMANDS.md

@@ -1,9 +1,4 @@
 MODEL: GPT-5.4-codex
-REASONING: high
-
+REASONING: low
 COMMAND:
-Execute exactly docs/pr/BUILD_PR_GAMES_94A_ASTEROIDS_NEW_PARALLEL_BURST_ALPHA.md.
-Modify only the exact target files listed in the PR doc.
-Do not expand scope.
-Package the delta zip to:
-<project folder>/tmp/BUILD_PR_GAMES_94A_ASTEROIDS_NEW_PARALLEL_BURST_ALPHA_delta.zip
+Append provided content to RULES.md and WORKFLOW.md without deleting or modifying existing content.

docs/dev/COMMIT_COMMENT.txt

@@ -1 +1 @@
-Accelerate asteroids_new with one larger non-destructive parallel adoption burst covering world, debug, and two entity files.
+Add TESTABILITY GATE and BUILD quality requirement without modifying existing content.

docs/dev/NEXT_COMMAND.txt

@@ -1 +1 @@
-After commit, inspect the delta and either pull one additional gameplay slice or validate before widening into systems.
+Next: enforce testable vertical slice builds across roadmap.

docs/dev/start_of_day/codex/RULES.md

@@ -77,3 +77,29 @@ Codex must report:
 - whether scope stayed clean
 - whether engine-core was untouched if expected
 - the ZIP output path under `<project folder>/tmp/`
+
+
+
+## 🚫 TESTABILITY GATE (NEW — REQUIRED)
+
+A BUILD PR must produce a testable result.
+
+Definition of testable:
+- Can be executed, loaded, or meaningfully validated (runtime, UI, or module level)
+- Not just structural (folders, placeholders, or isolated files)
+- Not a partial dependency chain that cannot run
+
+FAIL FAST if:
+- The change only copies files without enabling execution
+- The result cannot be smoke-tested
+- The change introduces a partial system with no entry point
+
+DO NOT EXECUTE:
+- Scaffolding-only PRs
+- Single-file migrations that do not integrate
+- Folder-only or placeholder-only changes
+
+Instead:
+- Expand the BUILD scope to a vertical slice
+- Or request a corrected BUILD PR with sufficient scope
+

docs/dev/start_of_day/codex/WORKFLOW.md

@@ -30,3 +30,19 @@
 - modify roadmap wording
 - touch start_of_day files
 - continue after a failed execution threshold
+
+
+
+## ✅ BUILD PR Quality Requirement (TESTABILITY)
+
+Every BUILD PR must result in a testable state.
+
+Preferred:
+- Vertical slice (feature, flow, or runnable subset)
+
+Avoid:
+- Incremental fragments that cannot run
+
+Rule of thumb:
+If it cannot be executed or meaningfully validated, it is not a valid BUILD.
+