[Bug]: agent_browser screenshot result lacks save confirmation, causing agents to report the screenshot wasn't saved

[JordanTheJet]

Affected component

tools

Severity

S3 - minor issue

Current behavior

The agent_browser browser backend's screenshot action returns the bare path passthrough from the agent-browser CLI — e.g. {"path": "..."} — with no independent save confirmation (no byte count, no saved: true flag, no file-existence check). At least one model (gpt-5.5, driving a headed browser) interpreted this as an unconfirmed/"empty" save and reported it could not confirm the screenshot was written, even though the PNG was written correctly on disk.

This is inconsistent with the rust_native backend, whose screenshot result includes "bytes": png.len() as positive confirmation.

Expected behavior

The agent_browser screenshot ToolResult should include an unambiguous save confirmation (verify the file exists + include a byte count and/or explicit saved: true), mirroring the rust_native backend, so models can reliably tell the screenshot succeeded.

Steps to reproduce

# Agent on any provider, default browser.backend = "agent_browser", headed
echo "Open https://example.com and screenshot it to C:/Users/<user>/AppData/Local/Temp/shot.png, then confirm it saved" \
  | zeroclaw agent -a <agent>

# The file is written, but the tool result is only:
#   {"path": "C:/Users/<user>/AppData/Local/Temp/shot.png"}
# Direct CLI check confirms the path is returned but nothing else:
agent-browser screenshot /tmp/probe.png --json
#   {"success":true,"data":{"path":"C:/Users/<user>/AppData/Local/Temp/probe.png"},"error":null}

Impact

Affected users: anyone using the default agent_browser backend whose agent takes screenshots.
Frequency: consistent for screenshot actions.
Consequence: agents hedge or report failure on successful screenshots; may trigger unnecessary retries or incorrect "couldn't save" conclusions. Cosmetic — no data loss.

Logs / stack traces

Model's final note (gpt-5.5):
"Screenshot note: the screenshot request returned an empty saved-path response,
 so I can't confirm from the tool output that it successfully wrote to
 C:/Users/<user>/AppData/Local/Temp/reddit-shot.png."

agent-browser screenshot --json (all variants return path, no bytes/confirmation):
{"success":true,"data":{"path":"C:/Users/<user>/AppData/Local/Temp/probe-shot.png"},"error":null}

Relevant code (zeroclaw/crates/zeroclaw-tools/src/browser.rs):
- screenshot branch ~L620 (agent_browser: passes CLI JSON through unchanged)
- to_result ~L952 (pretty-prints `data`; empty output when `data` is None)
- rust_native screenshot ~L1316 (includes "bytes": png.len())

ZeroClaw version

v0.8.1 (commit 6ce0473)

Rust version

rustc 1.93.1 (01f6ddf75 2026-02-11)

Operating system

Windows 11 Pro 10.0.26200

Regression?

Unknown

Pre-flight checks

• I reproduced this on the latest master branch or latest release.
• I redacted secrets, tokens, and personal data from all submitted content.