diff --git a/.github/Guidelines/Running-CLI.md b/.github/Guidelines/Running-CLI.md
index 1ff38483..d3cecb52 100644
--- a/.github/Guidelines/Running-CLI.md
+++ b/.github/Guidelines/Running-CLI.md
@@ -21,6 +21,8 @@ cd SOLUTION-ROOT
 & REPO-ROOT\.github\Scripts\copilotExecute.ps1 -Mode UnitTest -Executable PROJECT-NAME
 ```
 
+`-Mode` and `-Executable` are required.
+
 `-Configuration` and `-Platform` arguments are available to specify the target configuration:
 - When both arguments are omitted, the last build configuration will be picked up.
 - Both arguments should be omitted or not omitted at the same time.
diff --git a/.github/Guidelines/Running-UnitTest.md b/.github/Guidelines/Running-UnitTest.md
index 0ccb7b26..d3562740 100644
--- a/.github/Guidelines/Running-UnitTest.md
+++ b/.github/Guidelines/Running-UnitTest.md
@@ -21,6 +21,8 @@ cd SOLUTION-ROOT
 & REPO-ROOT\.github\Scripts\copilotExecute.ps1 -Mode UnitTest -Executable PROJECT-NAME
 ```
 
+`-Mode` and `-Executable` are required.
+
 `-Configuration` and `-Platform` arguments are available to specify the target configuration:
 - When both arguments are omitted, the last build configuration will be picked up.
 - Both arguments should be omitted or not omitted at the same time.
diff --git a/.github/Scripts/copilotDebug_RunCommand.ps1 b/.github/Scripts/copilotDebug_RunCommand.ps1
index cc3ed977..5bbe1b6e 100644
--- a/.github/Scripts/copilotDebug_RunCommand.ps1
+++ b/.github/Scripts/copilotDebug_RunCommand.ps1
@@ -1,8 +1,11 @@
 param(
-    [Parameter(Mandatory=$true)]
-    [string]$Command
+    [string]$Command = $null
 )
 
+if ([string]::IsNullOrEmpty($Command)) {
+    throw "\$Command parameter is required."
+}
+
 . $PSScriptRoot\copilotShared.ps1
 $cdbpath = GetCDBPath
 $commandLine = "echo .remote_exit | `"$($cdbpath)`" -remote npipe:server=.,pipe=VlppUnitTest -clines 0 -c `"$Command`""
diff --git a/.github/Scripts/copilotDebug_Start.ps1 b/.github/Scripts/copilotDebug_Start.ps1
index 485543c9..b504706e 100644
--- a/.github/Scripts/copilotDebug_Start.ps1
+++ b/.github/Scripts/copilotDebug_Start.ps1
@@ -1,8 +1,11 @@
 param(
-    [Parameter(Mandatory=$true)]
-    [string]$Executable
+    [string]$Executable = $null
 )
 
+if ([string]::IsNullOrEmpty($Executable)) {
+    throw "\$Executable parameter is required."
+}
+
 . $PSScriptRoot\copilotShared.ps1
 
 # Ensure the executable name has .exe extension
diff --git a/.github/Scripts/copilotExecute.ps1 b/.github/Scripts/copilotExecute.ps1
index 6162d232..848c7aa2 100644
--- a/.github/Scripts/copilotExecute.ps1
+++ b/.github/Scripts/copilotExecute.ps1
@@ -1,12 +1,17 @@
 param(
-    [Parameter(Mandatory=$true)]
-    [string]$Mode,
-    [Parameter(Mandatory=$true)]
-    [string]$Executable,
+    [string]$Mode = $null,
+    [string]$Executable = $null,
     [string]$Configuration = $null,
     [string]$Platform = $null
 )
 
+if ([string]::IsNullOrEmpty($Mode)) {
+    throw "\$Mode parameter is required."
+}
+if ([string]::IsNullOrEmpty($Executable)) {
+    throw "\$Executable parameter is required."
+}
+
 if (($Mode -ne "CLI") -and ($Mode -ne "UnitTest")) {
     throw "Invalid mode: $Mode. Allowed values are CLI or UnitTest."
 }
diff --git a/.github/TaskLogs/Copilot_Investigate.md b/.github/TaskLogs/Copilot_Investigate.md
new file mode 100644
index 00000000..c5aa7730
--- /dev/null
+++ b/.github/TaskLogs/Copilot_Investigate.md
@@ -0,0 +1 @@
+# !!!INVESTIGATE!!!
diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index e23ba8d2..7aa410dc 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -68,6 +68,7 @@ If you need to find any document for the current working task, they are in the `
 - `Copilot_Planning.md`
 - `Copilot_Execution.md`
 - `Copilot_KB.md`
+- `Copilot_Investigate.md`
 
 ### Important Rules for Writing Markdown Files
 
diff --git a/.github/prompts/0-scrum.prompt.md b/.github/prompts/0-scrum.prompt.md
index 22f05d3d..b5d4cec2 100644
--- a/.github/prompts/0-scrum.prompt.md
+++ b/.github/prompts/0-scrum.prompt.md
@@ -51,7 +51,7 @@ I am starting a fresh new request.
 Ignore this section if there is no "# Update" in the LATEST chat message
 I am going to propose some change to `Copilot_Scrum.md`.
 
-- Copy precisely my problem description in `# Update` from the LATEST chat message to the `# DESIGN REQUEST` section, with a new sub-section `## UPDATE`.
+- Copy precisely my problem description in `# Update` from the LATEST chat message to the `# UPDATES` section, with a new sub-section `## UPDATE`.
 - The new `## UPDATE` should be appended to the end of the existing `# UPDATES` section (aka before `# TASKS`).
 - When the number of tasks needs to be changed, due to inserting/removing/splitting/merging tasks:
   - Adjust task number of unaffected tasks accordingly, throughout the document.
diff --git a/.github/prompts/1-design.prompt.md b/.github/prompts/1-design.prompt.md
index 7c3985b2..6f2ff5bf 100644
--- a/.github/prompts/1-design.prompt.md
+++ b/.github/prompts/1-design.prompt.md
@@ -54,7 +54,7 @@ I am starting a fresh new request.
 Ignore this section if there is no "# Update" in the LATEST chat message
 I am going to propose some change to `Copilot_Task.md`.
 
-- Copy precisely my problem description in `# Update` from the LATEST chat message to the `# PROBLEM DESCRIPTION` section, with a new sub-section `## UPDATE`.
+- Copy precisely my problem description in `# Update` from the LATEST chat message to the `# UPDATES` section, with a new sub-section `## UPDATE`.
 - The new `## UPDATE` should be appended to the end of the existing `# UPDATES` section (aka before `# INSIGHTS AND REASONING`).
   - **NOTICE**: When the update is triggered by the automatic review process (aka `review.prompt.md`), do not insert such `## UPDATE`.
 - Follow my update to change the design document.
diff --git a/.github/prompts/investigate.prompt.md b/.github/prompts/investigate.prompt.md
new file mode 100644
index 00000000..2f425045
--- /dev/null
+++ b/.github/prompts/investigate.prompt.md
@@ -0,0 +1,154 @@
+# Scrum
+
+- Check out `Accessing Task Documents` and `Accessing Script Files` in `REPO-ROOT/.github/copilot-instructions.md` for context about mentioned `*.md` and `*.ps1` files.
+- Check out `External Tools Environment and Context` in `REPO-ROOT/.github/copilot-instructions.md` for accessing scripts for testing and debugging.
+- Check out `REPO-ROOT/Project.md` to find out what solutions you need to build.
+- All `*.md` and `*.ps1` files should exist; you should not create any new files unless explicitly instructed.
+  - The `Copilot_Investigate.md` file should already exist, it may or may not contain content from the last investigation.
+  - If you cannot find the file, you are looking at a wrong folder.
+- Following `Leveraging the Knowledge Base` in `REPO-ROOT/.github/copilot-instructions.md`, find knowledge and documents for this project in `REPO-ROOT/.github/KnowledgeBase/Index.md`.
+
+## Goal and Constraints
+
+- Your goal is to finish an investigation document in `Copilot_Investigate.md` to address a problem.
+- You are recommended to modify unit test, build, run, debug to understand the problem, or verify your root cause analysis during tracing a bug.
+
+## Copilot_Investigate.md Structure
+
+- `# !!!INVESTIGATE!!!`: This file always begins with this title.
+- `# PROBLEM DESCRIPTION`: An exact copy of the problem description I gave you.
+- `# UPDATES`
+  - `# (CONTINUE|REPORT)`: There could be multiple occurrences. Each one has an exact copy of the update description I gave you.
+- `# TEST`: Test cases to confirm or define the problem.
+- `# PROPOSALS`: A list of proposed solutions, followed by details about each proposal.
+  - `- No.X TITLE OF PROPOSAL`, with `[CONFIRMED]` or `[DENIED]` after the proposal is tested and proven to be correct or incorrect. X is a increasing number starting from 1.
+  - `## No.X TITLE OF PROPOSAL`: Details of the proposal.
+    - `### CODE CHANGE`: The change you have done to the source code to implement the proposal.
+    - `### (CONFIRMED|DENIED|DENIED BY USER)`: Appear after the proposal is tested and proven to be correct or incorrect, with a comprehensive explanation about why.
+
+## Step 1. Identify the Problem
+
+- The problem I would like to solve is in the chat messages sent with this request.
+- Find `# Repro` or `# Continue` or `# Report`.
+  - Ignore any of these titles in the chat history.
+  - If there is nothing: it means `# Continue`.
+
+### Repro the Problem (only when "# Repro" appears in the LATEST chat message)
+
+Ignore this section if there is no "# Repro" in the LATEST chat message
+I am starting a fresh new request.
+
+- You should override `Copilot_Investigate.md` with only one title `# !!!INVESTIGATE!!!`.
+  - At the moment, `Copilot_Investigate.md` may contain the last investigation, even it may look like the document is already finished for the current investigation, always clean it up.
+- After overriding, copy precisely my problem description in `# Repro` from the LATEST chat message under `# PROBLEM DESCRIPTION`.
+- Add empty `# UPDATES`, `# TEST` and `# PROPOSALS` sections.
+- Jump to `Step 2` directly.
+
+### Continue Investigation (only when "# Continue" appears in the LATEST chat message)
+
+Ignore this section if there is no "# Continue" in the LATEST chat message (or when the LATEST chat message has no content)
+I am going to propose some change to `Copilot_Investigate.md`.
+
+- When there is any content under `# Continue` in the LATEST chat message:
+  - Copy precisely my problem description in `# Continue` from the LATEST chat message to the `# UPDATES` section, with a new sub-section `## UPDATE`.
+  - The new `## UPDATE` should be appended to the end of the existing `# UPDATES` section (aka before `# TEST`).
+  - If I am not agree with any proposal marked with `[CONFIRMED]`:
+    - Mark these proposals with `[DENIED]`, change related `### CONFIRMED` in those proposals to `### DENIED BY USER`, and write a comprehensive explanation in each proposal about why.
+- Jump to `Step 5` directly.
+
+### Generate Report (only when "# Report" appears in the LATEST chat message)
+
+Ignore this section if there is no "# Report" in the LATEST chat message
+I am going to propose some change to `Copilot_Investigate.md`.
+
+- When there is any content under `# Report` in the LATEST chat message:
+  - Copy precisely my problem description in `# Report` from the LATEST chat message to the `# UPDATES` section, with a new sub-section `## UPDATE`.
+  - The new `## UPDATE` should be appended to the end of the existing `# UPDATES` section (aka before `# TEST`).
+  - If I am not agree with any proposal marked with `[CONFIRMED]`:
+    - Mark these proposals with `[DENIED]`, change related `### CONFIRMED` in those proposals to `### DENIED BY USER`, and write a comprehensive explanation in each proposal about why.
+- Add a `# REPORT` at the end of the document:
+  - You are going to explain all `[COMFIRMED]` proposals about why it work, how does it solve the issue.
+  - You are going to compare between any `[CONFIRMED]` proposals, explain how each one is better (pros) or worse (cons) than the others.
+- Skip all remaining steps, you are good from here.
+
+## Step 2. Construct Test Cases
+
+Only when I suggest that the problem is impossible to repro with test cases, write `N/A` under `# TEST` and skip `Step 2.`.
+
+- You are going to construct proper test cases to address the problem.
+- If I suggest a way to confirm the issue:
+  - Write the idea under `# TEST`.
+  - Finish actual test cases.
+  - Build the unit test to ensure test cases compile.
+- If I suggest that test cases already exist:
+  - Find the test cases and summarize the idea under `# TEST`.
+  - Build the unit test to ensure test cases compile.
+- If I did not suggest any way to confirm the issue:
+  - You need to come up with your own idea to confirm the issue.
+  - Write the idea under `# TEST`.
+  - Finish actual test cases.
+  - Build the unit test to ensure test cases compile.
+- Finish `# Test`
+  - Besides of the idea of the test cases, you should also understand the criteria of successful. Write them in `# TEST` as well.
+  - Passing test cases is the basic criteria, there might be other condition, make sure you are clear about that, and write them down in `# TEST`.
+  - Such condition usually including:
+    - Find out any clue in logs.
+    - Attach a debugger to confirm something happens or not.
+
+## Step 3. Confirm the Problem
+
+If `N/A` is written under `# TEST`, it means the problem is not possible to repro with test cases, skip this step.
+If the title is `# TEST [CONFIRMED]`, it means the problem is already proven confirmable by the test cases, skip this step.
+
+- Run the test cases and confirm that the problem is reproed.
+- If you cannot confirm, you need to figure out why, and jump back to `Step 2.` to adjust the test case.
+- If you can confirm, you need to update the title to `# TEST [CONFIRMED]`. Save your progress by:
+  - git commit all changes
+  - git push to the current branch, but if it fails because of needing to pull/merge or network issue, skip pushing.
+
+## Step 4. Propose Solutions
+
+Propose any solution you can think of and write them down in the document, you must save the document before trying each proposal.
+
+- Do necessary analysis to propose solutions to the problem.
+  - You are recommended to read related source code and documents to understand the problem.
+  - You are recommended to run the test cases, see is there something wrong.
+  - You are recommended to check logs from the test cases.
+  - You are recommended to debug the test cases.
+  - Try your best to collect any useful information.
+- It is fine to have multiple proposals, when you come out of any, record it under `# PROPOSALS`, a new list item and a new section should be added for each proposal:
+  - Add a new proposal with `- No.X TITLE OF PROPOSAL`
+  - Add a new proposal with `## No.X TITLE OF PROPOSAL` for details, you are going to add it at the end of the `# PROPOSALS`.
+    - With an empty section `### CODE CHANGE` at the end of the proposal.
+  - Confirmation of the proposal will be finished later, so do not include any mark for now.
+- Save your progress by:
+  - git commit all changes
+  - git push to the current branch, but if it fails because of needing to pull/merge or network issue, skip pushing.
+
+## Step 5. Confirm the Proposal
+
+- Find a proposal that has not been confirmed.
+  - Check out the list under `# PROPOSALS`, pick the first proposal that without `[CONFIRMED]` or `[DENIED]`.
+  - If every proposal is marked `[DENIED]`, you need to work out new proposals, jumpt to `Step 4`.
+  - If every proposal is marked, but some is `[CONFIRMED]`, you are good and stop here.
+    - If there is only one `[CONFIRMED]` proposal, reapply the change according to its `### CODE CHANGE` section, run the test cases to confirm all test cases passed and extra condition satisfied.
+- Understand and implement the proposal.
+- Run the test cases to confirm the proposal.
+  - Ensure all test cases passed.
+    - If related test cases failed, it means the proposal is denied.
+    - If unrelated test cases failed, it means the proposal introduce regression issues:
+      - Try to work out a fix, remember to update the current `## No.X TITLE OF PROPOSAL` with the fix details.
+      - Re-run the test cases until you come to a conclusion.
+  - Ensure all condition verified.
+    - You need to carefully read the `# TEST` section.
+    - You might be required to check logs or debug the test cases to confirm the condition.
+- If the proposal is proven to be useful, mark the proposal with `[CONFIRMED]`, and write a comprehensive explanation in `### CONFIRMED`.
+- If the proposal is proven to be denied, mark the proposal with `[DENIED]`, and write a comprehensive explanation in `### DENIED`.
+- After trying a proposal:
+  - You need to record what is your updating to the source code under `### CODE CHANGE` of the proposal.
+  - You need to record what you have done to confirm the problem under `### CONFIRMED` or `### DENIED` of the proposal.
+  - Save your progress by:
+    - git commit `Copilot_Investigate.md`.
+    - revert all other changes, so that you can continue for the next one, this is why it is important to record your change.
+    - git push to the current branch, but if it fails because of needing to pull/merge or network issue, skip pushing.
+  - Jump back to `Step 5` to try the next proposal.
diff --git a/AGENTS.md b/AGENTS.md
index 3226f4c8..d332f3b5 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -14,6 +14,7 @@ Read the first word of the request, and read an additional instruction file when
 - "execute": REPO-ROOT/.github/prompts/4-execution.prompt.md
 - "verify": REPO-ROOT/.github/prompts/5-verifying.prompt.md
 - "ask": REPO-ROOT/.github/prompts/ask.prompt.md
+- "investigate": REPO-ROOT/.github/prompts/investigate.prompt.md
 - "code": REPO-ROOT/.github/prompts/code.prompt.md
 - "kb": REPO-ROOT/.github/prompts/kb.prompt.md
 - "refine": REPO-ROOT/.github/prompts/refine.prompt.md
@@ -34,6 +35,7 @@ Read the first word of the request, and read an additional instruction file when
   - "plan"
   - "summary"
   - "execute"
+  - "investigate"
   - "review"
   - "kb"
 - Read the second word if it exists, convert it to a title `# THE-WORD`.
diff --git a/CLAUDE.md b/CLAUDE.md
index 3226f4c8..d332f3b5 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -14,6 +14,7 @@ Read the first word of the request, and read an additional instruction file when
 - "execute": REPO-ROOT/.github/prompts/4-execution.prompt.md
 - "verify": REPO-ROOT/.github/prompts/5-verifying.prompt.md
 - "ask": REPO-ROOT/.github/prompts/ask.prompt.md
+- "investigate": REPO-ROOT/.github/prompts/investigate.prompt.md
 - "code": REPO-ROOT/.github/prompts/code.prompt.md
 - "kb": REPO-ROOT/.github/prompts/kb.prompt.md
 - "refine": REPO-ROOT/.github/prompts/refine.prompt.md
@@ -34,6 +35,7 @@ Read the first word of the request, and read an additional instruction file when
   - "plan"
   - "summary"
   - "execute"
+  - "investigate"
   - "review"
   - "kb"
 - Read the second word if it exists, convert it to a title `# THE-WORD`.