diff --git a/commands/gsd/new-project.md b/commands/gsd/new-project.md
index 508b08dd9..339f50f96 100644
--- a/commands/gsd/new-project.md
+++ b/commands/gsd/new-project.md
@@ -9,6 +9,10 @@ allowed-tools:
   - Task
   - AskUserQuestion
 ---
+<runtime_note>
+**Copilot (VS Code):** Use `vscode_askquestions` wherever this workflow calls `AskUserQuestion`. They are equivalent — `vscode_askquestions` is the VS Code Copilot implementation of the same interactive question API.
+</runtime_note>
+
 <context>
 **Flags:**
 - `--auto` — Automatic mode. After config questions, runs research → requirements → roadmap without further interaction. Expects idea document via @ reference.
diff --git a/get-shit-done/bin/lib/init.cjs b/get-shit-done/bin/lib/init.cjs
index 544413d25..989f3ef84 100644
--- a/get-shit-done/bin/lib/init.cjs
+++ b/get-shit-done/bin/lib/init.cjs
@@ -276,7 +276,7 @@ function cmdInitNewProject(cwd, raw) {
       '.ex', '.exs',           // Elixir
       '.clj',                  // Clojure
     ]);
-    const skipDirs = new Set(['node_modules', '.git', '.planning', '.claude', '__pycache__', 'target', 'dist', 'build']);
+    const skipDirs = new Set(['node_modules', '.git', '.planning', '.claude', '.codex', '__pycache__', 'target', 'dist', 'build']);
     function findCodeFiles(dir, depth) {
       if (depth > 3) return false;
       let entries;
diff --git a/get-shit-done/workflows/new-project.md b/get-shit-done/workflows/new-project.md
index a5f50f8b9..d3861db9f 100644
--- a/get-shit-done/workflows/new-project.md
+++ b/get-shit-done/workflows/new-project.md
@@ -66,6 +66,29 @@ AGENT_SKILLS_ROADMAPPER=$(node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" a
 
 Parse JSON for: `researcher_model`, `synthesizer_model`, `roadmapper_model`, `commit_docs`, `project_exists`, `has_codebase_map`, `planning_exists`, `has_existing_code`, `has_package_file`, `is_brownfield`, `needs_codebase_map`, `has_git`, `project_path`.
 
+**Detect runtime and set instruction file name:**
+
+Derive `RUNTIME` from the invoking prompt's `execution_context` path:
+- Path contains `/.codex/` → `RUNTIME=codex`
+- Path contains `/.gemini/` → `RUNTIME=gemini`
+- Path contains `/.config/opencode/` or `/.opencode/` → `RUNTIME=opencode`
+- Otherwise → `RUNTIME=claude`
+
+If `execution_context` path is not available, fall back to env vars:
+```bash
+if [ -n "$CODEX_HOME" ]; then RUNTIME="codex"
+elif [ -n "$GEMINI_CONFIG_DIR" ]; then RUNTIME="gemini"
+elif [ -n "$OPENCODE_CONFIG_DIR" ] || [ -n "$OPENCODE_CONFIG" ]; then RUNTIME="opencode"
+else RUNTIME="claude"; fi
+```
+
+Set the instruction file variable:
+```bash
+if [ "$RUNTIME" = "codex" ]; then INSTRUCTION_FILE="AGENTS.md"; else INSTRUCTION_FILE="CLAUDE.md"; fi
+```
+
+All subsequent references to the project instruction file use `$INSTRUCTION_FILE`.
+
 **If `project_exists` is true:** Error — project already initialized. Use `/gsd:progress`.
 
 **If `has_git` is false:** Initialize git:
@@ -1106,18 +1129,18 @@ Use AskUserQuestion:
 
 **If "Review full file":** Display raw `cat .planning/ROADMAP.md`, then re-ask.
 
-**Generate or refresh project CLAUDE.md before final commit:**
+**Generate or refresh project instruction file before final commit:**
 
 ```bash
-node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" generate-claude-md
+node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" generate-claude-md --output "$INSTRUCTION_FILE"
 ```
 
-This ensures new projects get the default GSD workflow-enforcement guidance and current project context in `CLAUDE.md`.
+This ensures new projects get the default GSD workflow-enforcement guidance and current project context in `$INSTRUCTION_FILE`.
 
 **Commit roadmap (after approval or auto mode):**
 
 ```bash
-node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" commit "docs: create roadmap ([N] phases)" --files .planning/ROADMAP.md .planning/STATE.md .planning/REQUIREMENTS.md CLAUDE.md
+node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" commit "docs: create roadmap ([N] phases)" --files .planning/ROADMAP.md .planning/STATE.md .planning/REQUIREMENTS.md "$INSTRUCTION_FILE"
 ```
 
 ## 9. Done
@@ -1138,7 +1161,7 @@ Present completion summary:
 | Research       | `.planning/research/`       |
 | Requirements   | `.planning/REQUIREMENTS.md` |
 | Roadmap        | `.planning/ROADMAP.md`      |
-| Project guide  | `CLAUDE.md`                 |
+| Project guide  | `$INSTRUCTION_FILE`         |
 
 **[N] phases** | **[X] requirements** | Ready to build ✓
 ```
@@ -1220,7 +1243,7 @@ PHASE1_HAS_UI=$(echo "$PHASE1_SECTION" | grep -qi "UI hint.*yes" && echo "true"
 - `.planning/REQUIREMENTS.md`
 - `.planning/ROADMAP.md`
 - `.planning/STATE.md`
-- `CLAUDE.md`
+- `$INSTRUCTION_FILE` (`AGENTS.md` for Codex, `CLAUDE.md` for all other runtimes)
 
 </output>
 
@@ -1242,7 +1265,7 @@ PHASE1_HAS_UI=$(echo "$PHASE1_SECTION" | grep -qi "UI hint.*yes" && echo "true"
 - [ ] ROADMAP.md created with phases, requirement mappings, success criteria
 - [ ] STATE.md initialized
 - [ ] REQUIREMENTS.md traceability updated
-- [ ] CLAUDE.md generated with GSD workflow guidance
+- [ ] `$INSTRUCTION_FILE` generated with GSD workflow guidance (AGENTS.md for Codex, CLAUDE.md otherwise)
 - [ ] User knows next step is `/gsd:discuss-phase 1`
 
 **Atomic commits:** Each phase commits its artifacts immediately. If context is lost, artifacts persist.