playwright-trace-decoder-mcp MCP Server

MCP server for unpacking and analyzing Playwright trace.zip archives

Publisher claimed. No tool list reported, and Pod has not connected to this server.

Status

Pod has not dialled playwright-trace-decoder-mcp yet, so everything on this page is what its publisher reported rather than what we observed. Registries describe servers; they do not connect to them. Until a check runs, treat the tool list below as a claim.

Connect

Published as playwright-trace-decoder-mcp on npm. Runs locally.

Known issues

13 problems reported by people outside the maintainer team. Issues filed by the project's own owners, members and collaborators are excluded — those are release checklists and internal refactors, not things that will go wrong for you. Showing 10.

Most discussed

feat: add detect_performance_anomalies tool

Problem

Performance anomalies are frequently the real cause of what appear to be flaky timeouts. When heavy JS execution blocks the browser's main thread, Playwright's actionability checks silently time out — but the agent blames the selector, not performance.

Long Tasks (JS tasks >50ms) and frame drops during the failing step are recorded in Playwright's internal timing data but never surfaced by the MCP server.

What the agent gains

Direct empirical evidence that a timeout was caused

Read the thread · 2026-05-18 · closed · 1 comment

feat: add correlate_dom_and_network tool

Problem

The agent receives the HAR network log and DOM snapshots as two separate, flat text blocks. It must guess or hallucinate the causal link between a specific fetch response and the appearance of a new DOM node. This is the primary reason the agent misdiagnoses race conditions as selector failures.

Playwright captures three DOM snapshots per action (before, action, after) with millisecond-precision timestamps. The HAR file records network response completion times at the same pre

Read the thread · 2026-05-18 · closed · 1 comment

feat: add extract_trace_metadata_strict tool

Problem

The current parser silently breaks on several real-world Playwright configurations:

.pwtrace.zip extension — newer Playwright versions use this to prevent artifact naming collisions in CI. If the server filters strictly for .zip, modern traces fail to load.
Multi-retry archives — when a test suite uses retries: 2, a single downloaded archive may contain multiple disjointed sessions. The server must identify and isolate the specific retry that failed.
**HAR payloa

Read the thread · 2026-05-18 · closed · 1 comment

feat: add get_screenshot_at_failure tool (base64 JPEG from trace.zip)

Context

Playwright traces store screenshots as resources/page@<id>-<timestamp>.jpeg inside the zip. Currently when get_aria_accessibility_tree returns an empty document (e.g. captcha, blank page), the agent has no visual context. A base64 screenshot fills that gap.

Proposed tool

get_screenshot_at_failure — trace_path only.

Find all resources/page@*.jpeg entries in the zip
Parse timestamps from filenames
Return the screenshot whose timestamp is closest to (and bef

Read the thread · 2026-05-15 · closed · 0 comments

compare_traces: index-based alignment breaks when action sequences differ in length

Problem

compareTraces zips passing and failing actions by array index. If the failing run has an extra retry, a conditional navigation, or any action that doesn't appear in the passing run, everything after that point is misaligned — the diff becomes meaningless.

Fix

Implement fuzzy alignment before comparing: match actions by apiName + locator (or apiName alone when no locator is present) using a longest-common-subsequence approach. Only compare structurally matched pairs; report

Read the thread · 2026-05-15 · closed · 0 comments

Most recent

feat: cross-trace comparison + error signature grouping for flakiness analysis

What & Why

A single trace tells you what failed. Two traces (pass + fail of the same test) tell you why it's flaky. Playwright's retries + retain-on-failure mode saves both — this tool makes them comparable.

Error signature grouping (à la Sentry) lets an agent instantly determine if 10 parallel CI failures are all the same root cause or 10 different ones.

Tasks

Error signature generation

generate_error_signature tool — produces a stable hash from: test name + normaliz

Read the thread · 2026-05-15 · closed · 0 comments

feat: advanced diagnostic tools — race conditions, DOM delta, causal chain

What & Why

Move heavy analytical work from the LLM to the server. Instead of dumping raw data and asking the agent to reason about timing or DOM changes, the server does the deterministic computation and hands the agent a conclusion.

Tasks

`analyze_race_conditions`

Cross-reference action timings against concurrent network request lifecycles
Flag cases where a UI action fired before a dependent API response arrived (primary cause of flaky tests)

`get_dom_mutation_del

Read the thread · 2026-05-15 · closed · 0 comments

feat: get_aria_accessibility_tree — translate frame-snapshot to ARIA YAML

What & Why

frame-snapshot events contain the full serialized DOM at each action step — but raw DOM JSON is massively token-expensive for LLMs. Playwright's native ARIA snapshot format (YAML, semantic roles + text only) reduces token footprint by ~90% while giving the agent perfect context to suggest resilient locators like getByRole.

This is the highest-value single tool for improving AI agent accuracy on locator failures.

Tasks

Identify and extract frame-snapshot entries f

Read the thread · 2026-05-15 · closed · 0 comments

feat: context window protection — pagination + get_test_metadata tool

What & Why

Tools like get_action_timeline and get_console_errors can return hundreds of entries for long test runs — one big response blows the LLM context window and causes the "summarization loop" failure mode. We also need a lightweight metadata tool before any deep analysis.

Tasks

Add limit / offset params (Zod-validated) to get_action_timeline, get_console_errors, get_filtered_network_logs
Add get_test_metadata tool — returns test name, Playwright versio

Read the thread · 2026-05-15 · closed · 0 comments

fix: parser foundation — streaming JSONL, metadata.json, console text, trace cache

What & Why

Current parser loads the full trace into memory as a string — will OOM on traces >100MB (real enterprise suites). Also has two known bugs.

Tasks

Replace string concatenation with streaming JSONL parser (readline interface) to handle large traces without V8 OOM
Parse metadata.json from the zip (Playwright version, browser, viewport, test name, timestamps) — needed for get_test_metadata tool and future version-branching logic
Fix get_console_errors — `

Read the thread · 2026-05-15 · closed · 0 comments

See all 13 reports Pod holds for playwright-trace-decoder-mcp.

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