feat(coding-agent): add support for APPEND_SYSTEM.md to append instructions to system prompt (#716)

Co-authored-by: Jian Zhang <jzhang@yanhuangdata.com>
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Jian Zhang 2026-01-14 17:25:38 +08:00 committed by GitHub
parent 5279bb92da
commit 30a126f2bd
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2 changed files with 32 additions and 3 deletions

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@ -573,7 +573,7 @@ Use these for:
### Custom System Prompt
Replace the default system prompt entirely by creating a `SYSTEM.md` file:
Replace the default system prompt **entirely** by creating a `SYSTEM.md` file:
1. **Project-local:** `.pi/SYSTEM.md` (takes precedence)
2. **Global:** `~/.pi/agent/SYSTEM.md` (fallback)
@ -589,7 +589,16 @@ Focus on:
- Proper formatting
```
The `--system-prompt` CLI flag overrides both files. Use `--append-system-prompt` to add to (rather than replace) the prompt.
The `--system-prompt` CLI flag overrides both files.
### Appending to the System Prompt
To add instructions to the system prompt **without** replacing the default (preserving automatic loading of `AGENTS.md` context files, skills, and tools guidelines), create an `APPEND_SYSTEM.md` file:
1. **Project-local:** `.pi/APPEND_SYSTEM.md` (takes precedence)
2. **Global:** `~/.pi/agent/APPEND_SYSTEM.md` (fallback)
The `--append-system-prompt` CLI flag overrides both files.
### Custom Models and Providers

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@ -116,6 +116,23 @@ function discoverSystemPromptFile(): string | undefined {
return undefined;
}
/** Discover APPEND_SYSTEM.md file if no CLI append system prompt was provided */
function discoverAppendSystemPromptFile(): string | undefined {
// Check project-local first: .pi/APPEND_SYSTEM.md
const projectPath = join(process.cwd(), CONFIG_DIR_NAME, "APPEND_SYSTEM.md");
if (existsSync(projectPath)) {
return projectPath;
}
// Fall back to global: ~/.pi/agent/APPEND_SYSTEM.md
const globalPath = join(getAgentDir(), "APPEND_SYSTEM.md");
if (existsSync(globalPath)) {
return globalPath;
}
return undefined;
}
function buildSessionOptions(
parsed: Args,
scopedModels: ScopedModel[],
@ -128,8 +145,11 @@ function buildSessionOptions(
// Auto-discover SYSTEM.md if no CLI system prompt provided
const systemPromptSource = parsed.systemPrompt ?? discoverSystemPromptFile();
// Auto-discover APPEND_SYSTEM.md if no CLI append system prompt provided
const appendSystemPromptSource = parsed.appendSystemPrompt ?? discoverAppendSystemPromptFile();
const resolvedSystemPrompt = resolvePromptInput(systemPromptSource, "system prompt");
const resolvedAppendPrompt = resolvePromptInput(parsed.appendSystemPrompt, "append system prompt");
const resolvedAppendPrompt = resolvePromptInput(appendSystemPromptSource, "append system prompt");
if (sessionManager) {
options.sessionManager = sessionManager;