Add last_instructions configurable section

Expose lastInstructions as a customizable section across all 4 SDKs,
addressing review feedback about duplicate tool-efficiency blocks.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 2 people

docs/getting-started.md

@@ -1261,7 +1261,7 @@ const session = await client.createSession({
 });
 ```
 
-Available section IDs: `identity`, `tone`, `tool_efficiency`, `environment_context`, `code_change_rules`, `guidelines`, `safety`, `tool_instructions`, `custom_instructions`.
+Available section IDs: `identity`, `tone`, `tool_efficiency`, `environment_context`, `code_change_rules`, `guidelines`, `safety`, `tool_instructions`, `custom_instructions`, `last_instructions`.
 
 Each override supports four actions: `replace`, `remove`, `append`, and `prepend`. Unknown section IDs are handled gracefully — content is appended to additional instructions and a warning is emitted; `remove` on unknown sections is silently ignored.
 

dotnet/README.md

@@ -531,7 +531,7 @@ var session = await client.CreateSessionAsync(new SessionConfig
 });
 ```
 
-Available section IDs are defined as constants on `SystemPromptSections`: `Identity`, `Tone`, `ToolEfficiency`, `EnvironmentContext`, `CodeChangeRules`, `Guidelines`, `Safety`, `ToolInstructions`, `CustomInstructions`.
+Available section IDs are defined as constants on `SystemPromptSections`: `Identity`, `Tone`, `ToolEfficiency`, `EnvironmentContext`, `CodeChangeRules`, `Guidelines`, `Safety`, `ToolInstructions`, `CustomInstructions`, `LastInstructions`.
 
 Each section override supports four actions: `Replace`, `Remove`, `Append`, and `Prepend`. Unknown section IDs are handled gracefully: content is appended to additional instructions, and `Remove` overrides are silently ignored.
 

dotnet/src/Types.cs

@@ -1033,6 +1033,8 @@ public static class SystemPromptSections
     public const string ToolInstructions = "tool_instructions";
     /// <summary>Repository and organization custom instructions.</summary>
     public const string CustomInstructions = "custom_instructions";
+    /// <summary>End-of-prompt instructions: parallel tool calling, persistence, task completion.</summary>
+    public const string LastInstructions = "last_instructions";
 }
 
 /// <summary>

go/README.md

@@ -153,7 +153,7 @@ Event types: `SessionLifecycleCreated`, `SessionLifecycleDeleted`, `SessionLifec
 - `SystemMessage` (\*SystemMessageConfig): System message configuration. Supports three modes:
   - **append** (default): Appends `Content` after the SDK-managed prompt
   - **replace**: Replaces the entire prompt with `Content`
-  - **customize**: Selectively override individual sections via `Sections` map (keys: `SectionIdentity`, `SectionTone`, `SectionToolEfficiency`, `SectionEnvironmentContext`, `SectionCodeChangeRules`, `SectionGuidelines`, `SectionSafety`, `SectionToolInstructions`, `SectionCustomInstructions`; values: `SectionOverride` with `Action` and optional `Content`)
+  - **customize**: Selectively override individual sections via `Sections` map (keys: `SectionIdentity`, `SectionTone`, `SectionToolEfficiency`, `SectionEnvironmentContext`, `SectionCodeChangeRules`, `SectionGuidelines`, `SectionSafety`, `SectionToolInstructions`, `SectionCustomInstructions`, `SectionLastInstructions`; values: `SectionOverride` with `Action` and optional `Content`)
 - `Provider` (\*ProviderConfig): Custom API provider configuration (BYOK). See [Custom Providers](#custom-providers) section.
 - `Streaming` (bool): Enable streaming delta events
 - `InfiniteSessions` (\*InfiniteSessionConfig): Automatic context compaction configuration
@@ -218,7 +218,7 @@ session, err := client.CreateSession(ctx, &copilot.SessionConfig{
 })
 ```
 
-Available section constants: `SectionIdentity`, `SectionTone`, `SectionToolEfficiency`, `SectionEnvironmentContext`, `SectionCodeChangeRules`, `SectionGuidelines`, `SectionSafety`, `SectionToolInstructions`, `SectionCustomInstructions`.
+Available section constants: `SectionIdentity`, `SectionTone`, `SectionToolEfficiency`, `SectionEnvironmentContext`, `SectionCodeChangeRules`, `SectionGuidelines`, `SectionSafety`, `SectionToolInstructions`, `SectionCustomInstructions`, `SectionLastInstructions`.
 
 Each section override supports four actions:
 - **`replace`** — Replace the section content entirely

go/types.go

@@ -122,6 +122,7 @@ const (
 	SectionSafety             = "safety"
 	SectionToolInstructions   = "tool_instructions"
 	SectionCustomInstructions = "custom_instructions"
+	SectionLastInstructions   = "last_instructions"
 )
 
 // SectionOverride defines an override operation for a single system prompt section.

nodejs/README.md

@@ -501,7 +501,7 @@ const session = await client.createSession({
 });
 ```
 
-Available section IDs: `identity`, `tone`, `tool_efficiency`, `environment_context`, `code_change_rules`, `guidelines`, `safety`, `tool_instructions`, `custom_instructions`. Use the `SYSTEM_PROMPT_SECTIONS` constant for descriptions of each section.
+Available section IDs: `identity`, `tone`, `tool_efficiency`, `environment_context`, `code_change_rules`, `guidelines`, `safety`, `tool_instructions`, `custom_instructions`, `last_instructions`. Use the `SYSTEM_PROMPT_SECTIONS` constant for descriptions of each section.
 
 Each section override supports four actions:
 - **`replace`** — Replace the section content entirely

nodejs/src/types.ts

@@ -285,7 +285,8 @@ export type SystemPromptSection =
     | "guidelines"
     | "safety"
     | "tool_instructions"
-    | "custom_instructions";
+    | "custom_instructions"
+    | "last_instructions";
 
 /** Section metadata for documentation and tooling. */
 export const SYSTEM_PROMPT_SECTIONS: Record<SystemPromptSection, { description: string }> = {
@@ -298,6 +299,7 @@ export const SYSTEM_PROMPT_SECTIONS: Record<SystemPromptSection, { description:
     safety: { description: "Environment limitations, prohibited actions, security policies" },
     tool_instructions: { description: "Per-tool usage instructions" },
     custom_instructions: { description: "Repository and organization custom instructions" },
+    last_instructions: { description: "End-of-prompt instructions: parallel tool calling, persistence, task completion" },
 };
 
 /**

python/README.md

@@ -258,7 +258,7 @@ session = await client.create_session(
 )
 ```
 
-Available section IDs: `"identity"`, `"tone"`, `"tool_efficiency"`, `"environment_context"`, `"code_change_rules"`, `"guidelines"`, `"safety"`, `"tool_instructions"`, `"custom_instructions"`. Use the `SYSTEM_PROMPT_SECTIONS` dict for descriptions of each section.
+Available section IDs: `"identity"`, `"tone"`, `"tool_efficiency"`, `"environment_context"`, `"code_change_rules"`, `"guidelines"`, `"safety"`, `"tool_instructions"`, `"custom_instructions"`, `"last_instructions"`. Use the `SYSTEM_PROMPT_SECTIONS` dict for descriptions of each section.
 
 Each section override supports four actions:
 - **`replace`** — Replace the section content entirely

python/copilot/types.py

@@ -228,6 +228,7 @@ class Tool:
     "safety",
     "tool_instructions",
     "custom_instructions",
+    "last_instructions",
 ]
 
 SYSTEM_PROMPT_SECTIONS: dict[SystemPromptSection, str] = {
@@ -240,6 +241,7 @@ class Tool:
     "safety": "Environment limitations, prohibited actions, security policies",
     "tool_instructions": "Per-tool usage instructions",
     "custom_instructions": "Repository and organization custom instructions",
+    "last_instructions": "End-of-prompt instructions: parallel tool calling, persistence, task completion",
 }