diff --git a/docs_build/dev/ProjectInstructions/README.txt b/docs_build/dev/ProjectInstructions/README.txt
index 54e708e9c..a520a1f2c 100644
--- a/docs_build/dev/ProjectInstructions/README.txt
+++ b/docs_build/dev/ProjectInstructions/README.txt
@@ -45,3 +45,4 @@ Addendum index:
 - Canonical Repository Structure: project-instructions/addendums/canonical-repository-structure.md
 - Test Structure Standardization: project-instructions/addendums/test-structure-standardization.md
 - Legacy Migration Policy: project-instructions/addendums/legacy-migration-policy.md
+- Assistant Execution Modes: project-instructions/addendums/assistant-execution-modes.md
diff --git a/project-instructions/addendums/assistant-execution-modes.md b/project-instructions/addendums/assistant-execution-modes.md
new file mode 100644
index 000000000..6d7928669
--- /dev/null
+++ b/project-instructions/addendums/assistant-execution-modes.md
@@ -0,0 +1,120 @@
+# Assistant Execution Modes
+
+## Purpose
+
+Standardize request interpretation and expected outputs for Review, Owner, Build PR, Continue, Challenge, and Stop Gate workflows.
+
+## Command Modes
+
+### Review
+
+Expected Output:
+- Findings
+- Risks
+- Recommendations
+
+Do Not Output:
+- PRs
+- Implementation plans
+
+### Owner
+
+Expected Output:
+- Decisions
+- Governance direction
+- Standards
+
+Do Not Output:
+- Detailed implementation
+
+### Build PR
+
+Expected Output:
+- Single Codex work order
+- May contain multiple sequential PRs belonging to the same workstream
+- Copy/paste ready for execution
+
+Should Include:
+- Start gates
+- Changes
+- Validation
+- Commit names
+- Stop point
+
+Do Not Output:
+- Design discussion
+- Alternatives
+- Rationale
+- Architecture brainstorming
+
+### Continue
+
+Expected Output:
+- Next sequential executable PR
+- Next sequential work order
+
+Do Not Output:
+- New ideas
+- Re-analysis
+- Additional brainstorming
+
+### Challenge
+
+Expected Output:
+- Risks
+- Contradictions
+- Better alternatives
+
+Do Not Output:
+- Immediate implementation
+
+### Stop Gate
+
+Expected Output:
+- Why work should stop
+- Required corrections
+
+Allowed Reasons:
+- Governance conflict
+- Architecture conflict
+- Security risk
+- Data loss risk
+- Major technical debt increase
+
+## Additional Definitions
+
+### Follow Project Instructions
+
+Meaning:
+- Use existing governance
+- Do not redesign process
+
+### Build the PR
+
+Meaning:
+- Produce Codex executable work order immediately
+
+### Continue
+
+Meaning:
+- Produce next sequential work item
+
+### No zip file
+
+Meaning:
+- Generate instructions only
+- Do not expect artifact review
+
+### You are owner
+
+Meaning:
+- Make decisions
+- Do not ask for direction unless blocked
+
+### Done for the day
+
+Meaning:
+- Finish commits
+- Merge
+- Push
+- Create next-day start document