feat: V5 preamble — "not present" replaces "truncated" for MCP configs

- Add V5_PREAMBLE_TEMPLATE: opens with "Local source files are not
  present", mandatory 4-step workflow, concise tool selection table.
  25% shorter than V4 (removes Workflows, Output Formatting, Common
  Mistakes, Query Patterns sections).
- Switch preamble injection and system prompt from V4 to V5 for all
  MCP modes (sourcegraph_full, sourcegraph_base, artifact_full).
- Update SG_TOOL_REFERENCE note: "not present" instead of "truncated".
- Add Dockerfile.artifact_only fallback to Dockerfile.sg_only in
  sdlc_suite_2config.sh for tasks that lack artifact-specific images.
- Keep V4_PREAMBLE_TEMPLATE as deprecated reference.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sjarmak

agents/claude_baseline_agent.py

@@ -98,10 +98,80 @@
 - `deepsearch` — AI-powered deep analysis (async: returns a polling link)
 - `deepsearch_read` — read Deep Search results (call 60+ seconds after deepsearch)
 
-Note: Sourcegraph indexes the remote repository. Local source files may be truncated — use Sourcegraph to read code.
+Note: Sourcegraph indexes the remote repository. Local source files are not present — use Sourcegraph to read code.
 """
 
-# V4 Preamble template for MCP instruction injection.
+# V5 Preamble template for MCP instruction injection (current official).
+# No truncation language — local source files simply aren't present.
+# 25% shorter than V4: removes Workflows, Output Formatting, Common Mistakes, Query Patterns.
+# {repo_scope} is replaced at runtime with the target repository filter.
+V5_PREAMBLE_TEMPLATE = """# IMPORTANT: Source Code Access
+
+**Local source files are not present.** Your workspace does not contain source code. You **MUST** use Sourcegraph MCP tools to discover, read, and understand code before making any changes.
+
+{repo_scope}
+
+## Required Workflow
+
+1. **Search first** — Use MCP tools to find relevant files and understand existing patterns
+2. **Read remotely** — Use `sg_read_file` to read full file contents from Sourcegraph
+3. **Edit locally** — Use Edit, Write, and Bash to create or modify files in your working directory
+4. **Verify locally** — Run tests with Bash to check your changes
+
+## Tool Selection
+
+| Goal | Tool |
+|------|------|
+| Exact symbol/string | `sg_keyword_search` |
+| Concepts/semantic search | `sg_nls_search` |
+| Trace usage/callers | `sg_find_references` |
+| See implementation | `sg_go_to_definition` |
+| Read full file | `sg_read_file` |
+| Browse structure | `sg_list_files` |
+| Find repos | `sg_list_repos` |
+| Search commits | `sg_commit_search` |
+| Track changes | `sg_diff_search` |
+| Compare versions | `sg_compare_revisions` |
+
+**Decision logic:**
+1. Know the exact symbol? → `sg_keyword_search`
+2. Know the concept, not the name? → `sg_nls_search`
+3. Need definition of a symbol? → `sg_go_to_definition`
+4. Need all callers/references? → `sg_find_references`
+5. Need full file content? → `sg_read_file`
+
+## Scoping (Always Do This)
+
+```
+repo:^github.com/ORG/REPO$           # Exact repo (preferred)
+repo:github.com/ORG/                 # All repos in org
+file:.*\\.ts$                         # TypeScript only
+file:src/api/                        # Specific directory
+```
+
+Start narrow. Expand only if results are empty.
+
+## Efficiency Rules
+
+- Chain searches logically: search → read → references → definition
+- Don't re-search for the same pattern; use results from prior calls
+- Prefer `sg_keyword_search` over `sg_nls_search` when you have exact terms
+- Read 2-3 related files before synthesising, rather than one at a time
+- Don't read 20+ remote files without writing code — once you understand the pattern, start implementing
+
+## If Stuck
+
+If MCP search returns no results:
+1. Broaden the search query (synonyms, partial identifiers)
+2. Try `sg_nls_search` for semantic matching
+3. Use `sg_list_files` to browse the directory structure
+4. Use `sg_list_repos` to verify the repository name
+
+---
+
+"""
+
+# V4 Preamble template (DEPRECATED — kept for reference).
 # Skill-style guidance: tool selection, scoping, context-aware behavior.
 # No mandatory workflow mandates — teaches effective MCP usage by example.
 # {repo_scope} is replaced at runtime with the target repository filter.
@@ -389,11 +459,10 @@ def create_run_agent_commands(self, instruction: str) -> list[ExecInput]:
         # Get repo display name for MCP prompts (centralized resolution)
         repo_display = self._get_repo_display()
 
-        # For hybrid MCP modes, prepend V4 preamble to the instruction text.
+        # For hybrid MCP modes, prepend V5 preamble to the instruction text.
         if mcp_type in ("sourcegraph_full", "sourcegraph_base", "artifact_full"):
-            # --- V4 Preamble ---
-            # Skill-style guidance: tool selection, scoping, context-aware behavior.
-            # No mandatory workflow mandates — teaches effective MCP usage by example.
+            # --- V5 Preamble ---
+            # Leads with "files not present", mandatory workflow, concise tool guidance.
             if repo_display != "the codebase":
                 sg_repo_full = f"github.com/{repo_display}"
                 repo_scope = (
@@ -408,7 +477,7 @@ def create_run_agent_commands(self, instruction: str) -> list[ExecInput]:
                     "before searching.\n"
                 )
 
-            mcp_preamble = V4_PREAMBLE_TEMPLATE.format(repo_scope=repo_scope)
+            mcp_preamble = V5_PREAMBLE_TEMPLATE.format(repo_scope=repo_scope)
             instruction = mcp_preamble + instruction
 
             # Artifact-full: append guidance about expressing changes as diffs
@@ -558,15 +627,13 @@ def create_run_agent_commands(self, instruction: str) -> list[ExecInput]:
             system_prompt_append = EVALUATION_CONTEXT_PROMPT + "\n\n---\n\n" + mcp_system_prompt
 
         elif mcp_type in ("sourcegraph_full", "sourcegraph_base", "sourcegraph_isolated", "artifact_full"):
-            # V4 system prompt: lightweight reinforcement (detailed guidance is in the instruction preamble).
+            # V5 system prompt: reinforces that local source is absent, not truncated.
             if repo_display != "the codebase":
                 repo_filter_system = f"Sourcegraph repository: github.com/{repo_display}\nFor keyword_search: repo:^github.com/{repo_display}$ YourSearchTerm"
             else:
                 repo_filter_system = "Use list_repos to discover available repositories first."
 
-            mcp_system_prompt = f"""You have Sourcegraph MCP tools available. Use them to search, read, and navigate the codebase before making changes.
-
-Local source files may be truncated or unavailable. Use Sourcegraph to read and understand code, then make edits to local files based on what you learned. Run tests locally to verify your changes.
+            mcp_system_prompt = f"""IMPORTANT: Local source files are not present. You MUST use Sourcegraph MCP tools to discover and read code, then create or edit local files based on what you learn. Run tests locally to verify your changes.
 
 {repo_filter_system}"""
             system_prompt_append = EVALUATION_CONTEXT_PROMPT + "\n\n---\n\n" + mcp_system_prompt

configs/sdlc_suite_2config.sh

@@ -233,16 +233,22 @@ _sdlc_run_single() {
 
     elif [ "$config" = "artifact_full" ]; then
         local artifact="${task_path}/environment/Dockerfile.artifact_only"
-        if [ ! -f "$artifact" ]; then
-            echo "ERROR: Missing Dockerfile.artifact_only for $task_id at $artifact"
+        local chosen_dockerfile=""
+        if [ -f "$artifact" ]; then
+            chosen_dockerfile="Dockerfile.artifact_only"
+        elif [ -f "${task_path}/environment/Dockerfile.sg_only" ]; then
+            echo "WARNING: No Dockerfile.artifact_only for $task_id — falling back to Dockerfile.sg_only"
+            chosen_dockerfile="Dockerfile.sg_only"
+        else
+            echo "ERROR: No Dockerfile.artifact_only or Dockerfile.sg_only for $task_id"
             return 1
         fi
 
         temp_task_dir="/tmp/artifact_${task_id}"
         rm -rf "$temp_task_dir"
         mkdir -p "$temp_task_dir"
         cp -a "${task_path}/." "${temp_task_dir}/"
-        cp "${temp_task_dir}/environment/Dockerfile.artifact_only" "${temp_task_dir}/environment/Dockerfile"
+        cp "${temp_task_dir}/environment/${chosen_dockerfile}" "${temp_task_dir}/environment/Dockerfile"
         run_task_path="$temp_task_dir"
     fi