Proposal: fix agent-evolver — use Edit tool for surgical file changes instead of Write tool to prevent content regression #5736

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opened 2026-04-09 08:55:04 +00:00 by HAL9000 · 1 comment

HAL9000 commented

2026-04-09 08:55:04 +00:00

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Agent Improvement Proposal

Pattern Detected

Type: workflow_fix
Affected Agent: agent-evolver
Evidence: PR #4617 received REQUEST_CHANGES from human reviewer freemo (2026-04-08T23:39:17Z). The review identified a critical regression: continuous-pr-reviewer.md lost ~8,192 bytes (~35% of the file) because the agent-evolver replaced the entire file instead of making a surgical addition.

Detailed Evidence

From the PR #4617 review by freemo:

[CRITICAL REGRESSION] continuous-pr-reviewer.md Has Lost ~8KB of Content

The branch version of continuous-pr-reviewer.md is 15,377 bytes vs. the master version at 23,569 bytes — a loss of ~8,192 bytes (~35% of the file). The PR has silently deleted two entire sections that exist in master:

## Automation Tracking System — The entire tracking issue management system is gone.

## Inter-Agent Coordination — The check_other_agents_activity() and announce_urgent_issue() functions are gone.

The PR description says it only added a "primary CI reporter" note to continuous-pr-reviewer.md. Instead, it has replaced the entire file with an older/different version that is missing significant functionality. This is a silent regression that would break the automation tracking system if merged.

The root cause is in the agent-evolver's implementation workflow. When implementing an approved proposal, the agent:

Reads the current agent file
Applies the change conceptually
Writes the entire file back using the Write tool

This approach is fragile because:

The agent's context may have an outdated version of the file (from when it was read earlier in the session)
The agent may inadvertently omit sections it didn't focus on
Large files are especially vulnerable — the agent may truncate or drop sections

Proposed Change

Update the agent-evolver's implementation workflow (Step 5: "Check for APPROVED proposals") to explicitly require using the Edit tool for surgical changes rather than the Write tool for full file replacement:

# When implementing an approved proposal:
agent_file = ".opencode/agents/<agent_name>.md"

# CRITICAL: Use Edit tool for surgical changes, NOT Write tool
# The Edit tool replaces only the specific text that needs changing.
# The Write tool replaces the ENTIRE file and risks losing content.

# Step 1: Read the CURRENT file from the clone (not from memory)
git fetch origin && git checkout master && git reset --hard origin/master
current_content = read agent_file from disk

# Step 2: Identify the MINIMAL change needed
# Only modify the specific section, paragraph, or line that addresses the pattern.
# Do NOT rewrite sections that are not related to the fix.

# Step 3: Apply the change using Edit tool (oldString → newString)
# The Edit tool will fail if oldString is not found — this is a safety check.
# If the file has changed since the proposal was written, re-read and re-apply.

# Step 4: Verify the change is minimal
# Check that the file size after editing is within 10% of the original size.
# If the file shrank by more than 10%, something was accidentally deleted.
# Abort and re-read the file if this happens.

Additionally, add a pre-commit size check to the implementation workflow:

# Before committing:
original_size = wc -c < original_file
new_size = wc -c < modified_file
if new_size < original_size * 0.9:
    ERROR: "File shrank by more than 10% — possible content loss. Aborting."
    # Re-read the file and re-apply the change surgically

Expected Impact

Prevents content regression: Using Edit tool ensures only the targeted text is changed; all other content is preserved
Faster human approval: PRs that don't accidentally delete content will pass review more easily
Reduces rework: Avoids the cycle of REQUEST_CHANGES → fix → re-review
Safer implementation: The Edit tool's oldString not found error acts as a safety check that the file hasn't changed unexpectedly

Risk Assessment

Low risk: This is a pure workflow improvement — changing HOW the agent-evolver implements changes, not WHAT it changes.
Potential concern: Some changes may require adding entirely new sections (not editing existing ones). Mitigation: For new sections, the agent should append to the end of the file or insert at a specific location using Edit tool with a known anchor string.
Potential concern: The Edit tool requires exact string matching. If the file has changed since the proposal was written, the oldString may not match. Mitigation: The agent should always re-read the file from the clone immediately before applying the edit.

This is a proposal from the agent evolver. A human must approve this issue before the change will be implemented. To approve: remove the needs feedback label, add State/Verified, or comment with approval.

Automated by CleverAgents Bot
Supervisor: Agent Evolver | Agent: agent-evolver

## Agent Improvement Proposal ### Pattern Detected **Type**: workflow_fix **Affected Agent**: `agent-evolver` **Evidence**: PR #4617 received REQUEST_CHANGES from human reviewer `freemo` (2026-04-08T23:39:17Z). The review identified a **critical regression**: `continuous-pr-reviewer.md` lost ~8,192 bytes (~35% of the file) because the agent-evolver replaced the entire file instead of making a surgical addition. ### Detailed Evidence From the PR #4617 review by `freemo`: > **[CRITICAL REGRESSION] `continuous-pr-reviewer.md` Has Lost ~8KB of Content** > > The branch version of `continuous-pr-reviewer.md` is **15,377 bytes** vs. the master version at **23,569 bytes** — a loss of ~8,192 bytes (~35% of the file). The PR has silently **deleted** two entire sections that exist in master: > > - **`## Automation Tracking System`** — The entire tracking issue management system is gone. > - **`## Inter-Agent Coordination`** — The `check_other_agents_activity()` and `announce_urgent_issue()` functions are gone. > > The PR description says it only added a "primary CI reporter" note to `continuous-pr-reviewer.md`. Instead, it has **replaced the entire file** with an older/different version that is missing significant functionality. This is a **silent regression** that would break the automation tracking system if merged. The root cause is in the agent-evolver's implementation workflow. When implementing an approved proposal, the agent: 1. Reads the current agent file 2. Applies the change conceptually 3. Writes the **entire file** back using the Write tool This approach is fragile because: - The agent's context may have an outdated version of the file (from when it was read earlier in the session) - The agent may inadvertently omit sections it didn't focus on - Large files are especially vulnerable — the agent may truncate or drop sections ### Proposed Change Update the agent-evolver's implementation workflow (Step 5: "Check for APPROVED proposals") to explicitly require using the **Edit tool** for surgical changes rather than the Write tool for full file replacement: ``` # When implementing an approved proposal: agent_file = ".opencode/agents/<agent_name>.md" # CRITICAL: Use Edit tool for surgical changes, NOT Write tool # The Edit tool replaces only the specific text that needs changing. # The Write tool replaces the ENTIRE file and risks losing content. # Step 1: Read the CURRENT file from the clone (not from memory) git fetch origin && git checkout master && git reset --hard origin/master current_content = read agent_file from disk # Step 2: Identify the MINIMAL change needed # Only modify the specific section, paragraph, or line that addresses the pattern. # Do NOT rewrite sections that are not related to the fix. # Step 3: Apply the change using Edit tool (oldString → newString) # The Edit tool will fail if oldString is not found — this is a safety check. # If the file has changed since the proposal was written, re-read and re-apply. # Step 4: Verify the change is minimal # Check that the file size after editing is within 10% of the original size. # If the file shrank by more than 10%, something was accidentally deleted. # Abort and re-read the file if this happens. ``` Additionally, add a **pre-commit size check** to the implementation workflow: ``` # Before committing: original_size = wc -c < original_file new_size = wc -c < modified_file if new_size < original_size * 0.9: ERROR: "File shrank by more than 10% — possible content loss. Aborting." # Re-read the file and re-apply the change surgically ``` ### Expected Impact - **Prevents content regression**: Using Edit tool ensures only the targeted text is changed; all other content is preserved - **Faster human approval**: PRs that don't accidentally delete content will pass review more easily - **Reduces rework**: Avoids the cycle of REQUEST_CHANGES → fix → re-review - **Safer implementation**: The Edit tool's `oldString not found` error acts as a safety check that the file hasn't changed unexpectedly ### Risk Assessment - **Low risk**: This is a pure workflow improvement — changing HOW the agent-evolver implements changes, not WHAT it changes. - **Potential concern**: Some changes may require adding entirely new sections (not editing existing ones). Mitigation: For new sections, the agent should append to the end of the file or insert at a specific location using Edit tool with a known anchor string. - **Potential concern**: The Edit tool requires exact string matching. If the file has changed since the proposal was written, the oldString may not match. Mitigation: The agent should always re-read the file from the clone immediately before applying the edit. --- *This is a proposal from the agent evolver. A human must approve this issue before the change will be implemented. To approve: remove the `needs feedback` label, add `State/Verified`, or comment with approval.* --- **Automated by CleverAgents Bot** Supervisor: Agent Evolver | Agent: agent-evolver

HAL9000 added the

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2026-04-09 08:56:16 +00:00

HAL9000 commented

2026-04-09 10:09:17 +00:00

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Owner

Closing as duplicate of #5773 which was created by another agent-evolver instance for the same pattern (agent-evolver file replacement regression). Please see #5773 for the proposal.

Automated by CleverAgents Bot
Supervisor: Agent Evolver | Agent: agent-evolver

Closing as duplicate of #5773 which was created by another agent-evolver instance for the same pattern (agent-evolver file replacement regression). Please see #5773 for the proposal. --- **Automated by CleverAgents Bot** Supervisor: Agent Evolver | Agent: agent-evolver

HAL9000 closed this issue

2026-04-09 10:12:55 +00:00

HAL9000 referenced this issue

2026-04-09 11:52:09 +00:00

[AUTO-EVLV] Agent Evolution Report (Cycle 17) #5922