mlb-league-state-reader

name: mlb-league-state-reader description: Parses Yahoo Fantasy Baseball league state (roster, standings, current matchup, FAAB remaining, free agents) from authenticated Yahoo team pages via Claude-in-Chrome browser automation, then grounds it against league-config.md and team-profile.md to emit a normalized league-state bundle every other agent can consume without re-scraping. Use when the coach or any downstream agent needs to read Yahoo roster, refresh team profile, pull league state, get current matchup, check FAAB remaining, list free agents, or when user mentions "what's on my roster", "who am I playing this week", "how much FAAB do I have left", or "refresh my team".

MLB League State Reader

Table of Contents

• Example
• Workflow
• Degraded Mode
• Guardrails
• Quick Reference

Example

Scenario: Morning brief run on 2026-04-17. Coach needs current roster, matchup, FAAB, and standings before launching lineup-optimizer.

Inputs read first:

• yahoo-mlb/context/league-config.md (league ID 23756, team 5, 12 teams, 5x5 cats)
• yahoo-mlb/context/team-profile.md (prior known roster skeleton)

Chrome navigation sequence (authenticated):

1. https://baseball.fantasysports.yahoo.com/b1/23756/5 — roster with today's opponents per player
2. https://baseball.fantasysports.yahoo.com/b1/23756?lhst=stand — standings + category ranks
3. https://baseball.fantasysports.yahoo.com/b1/23756/matchup — this week's head-to-head vs Los Doyers
4. https://baseball.fantasysports.yahoo.com/b1/23756/transactions — FAAB spent to date → remaining
5. https://baseball.fantasysports.yahoo.com/b1/23756/players?status=A — top free agents (page 1)

Extracted bundle:

Outputs written:

• context/team-profile.md — roster snapshot updated in place (slot, player, MLB team, today's opp, status)
• signals/2026-04-17-league-state.md — signal file with YAML frontmatter, source_urls, confidence

Every downstream agent (lineup-optimizer, waiver-analyst, category-strategist) now reads this signal file and team-profile.md rather than re-scraping Yahoo.

Workflow

Copy this checklist and track progress:

League State Reader Progress:
- [ ] Step 1: Read context files (league-config.md + team-profile.md)
- [ ] Step 2: Pull Yahoo pages via Claude-in-Chrome (5 URLs)
- [ ] Step 3: Parse roster, standings, matchup, FAAB, free agents
- [ ] Step 4: Update team-profile.md in place
- [ ] Step 5: Emit signal file with frontmatter + source_urls

Step 1: Read context files

Load the authoritative contract and the last known state before touching Yahoo. This both verifies the league ID/URL and provides the skeleton to diff against.

• Read yahoo-mlb/context/league-config.md — confirm league ID 23756, team 5, roster shape (C/1B/2B/3B/SS/3OF/2UTIL/3SP/2RP/5P/3BN/3IL = 26), FAAB budget $100
• Read yahoo-mlb/context/team-profile.md — capture prior FAAB remaining, prior roster for diff
• Read yahoo-mlb/context/frameworks/signal-framework.md — confirm signal file format
• Read yahoo-mlb/context/frameworks/data-sources.md — confirm the 5 Yahoo URLs

Step 2: Pull Yahoo pages via Claude-in-Chrome

The user is already authenticated in the browser. Navigate in order; parse page text; if any step fails, jump to Degraded Mode for that specific URL only (do not abort the whole run). See resources/methodology.md for the exact tool-call sequence and page-parsing patterns.

• Team page: https://baseball.fantasysports.yahoo.com/b1/23756/5
• Standings: https://baseball.fantasysports.yahoo.com/b1/23756?lhst=stand
• Matchup: https://baseball.fantasysports.yahoo.com/b1/23756/matchup
• Transactions (for FAAB): https://baseball.fantasysports.yahoo.com/b1/23756/transactions
• Free agents: https://baseball.fantasysports.yahoo.com/b1/23756/players?status=A

Step 3: Parse and normalize

Extract structured data from each page. See resources/methodology.md for row-level parsing logic, and resources/methodology.md for how to reconstruct FAAB remaining from the transactions log.

• Roster: for each of 26 slots, capture {slot, player, mlb_team, opp_today, status: active|IL|DTD|NA|BN}
• Standings: W-L-T record, rank, per-category rank (10 cats)
• Matchup: opponent name, live scoreline by category (W-L-T across the 10 cats so far this week)
• FAAB: sum all -$N entries from transactions history this season; remaining = $100 - total spent
• Free agents: capture top 25 by rostered% — enough for waiver-analyst to start ranking

Step 4: Update team-profile.md in place

See resources/template.md for the exact output shape. Overwrite the existing file (not append); this file is meant to always reflect "as of the latest run."

• Header: ## As of YYYY-MM-DD
• State table: record, rank, FAAB remaining, current opponent, acquisitions used, IL slots used
• Roster snapshot: full 26-slot YAML block
• Open questions: empty unless a page failed

Step 5: Emit signal file

Write yahoo-mlb/signals/YYYY-MM-DD-league-state.md with YAML frontmatter per the signal framework. Every URL navigated must appear in source_urls. Degraded fetches drop confidence to 0.5; full-failure fields drop to 0.3 and are flagged. See resources/template.md.

• Frontmatter: type: league-state, date, emitted_by: mlb-league-state-reader, confidence, source_urls[]
• Body: roster table, standings table, matchup table, FAAB ledger, top-25 free agents
• Validate via mlb-signal-emitter before writing (if that skill is available in this run); otherwise write directly

Degraded Mode

Chrome can fail for several reasons: tab not open, session expired, Yahoo rate-limiting, 500 error, unreadable DOM. Never abort the whole run. Fail gracefully per-URL.

Per-URL fallback decision tree:

User-paste template (reuse for any Yahoo page):

"I couldn't reach {URL}. Please copy the visible table on that page (select all, paste into chat) and I'll extract the fields I need from your paste."

Parse the pasted text with the same regex/row patterns as the live page. See resources/methodology.md.

Guardrails

1. Never assume the roster is still what it was yesterday. Waivers clear daily and trades can fire any time. Always re-read the Yahoo team page at the start of every run, even if team-profile.md looks fresh.

2. FAAB remaining is derived, not displayed. Yahoo's UI sometimes shows "FAAB Balance" and sometimes doesn't. The authoritative computation is: $100 minus sum of all winning bids on the transactions page this season. Do not trust a single visible number over the ledger.

3. Cite every URL. The signal file's source_urls: list must contain every Yahoo page actually visited. If a page was skipped because of degradation, note it in the signal body, not silently.

4. Do not re-scrape downstream. Once this skill has emitted today's league-state signal, lineup-optimizer / waiver-analyst / category-strategist MUST read that signal rather than re-visit Yahoo. Re-scraping wastes tokens and risks drift.

5. Overwrite team-profile.md; append nowhere. This file is "current state." Preserving yesterday's roster pollutes it. The append-only log lives in tracker/decisions-log.md, not here.

6. Status values are normalized enums. Map Yahoo's labels (P, DTD, IL-10, IL-60, NA, SUSP) to the normalized enum: active | BN | IL | DTD | NA | SUSP. Downstream agents branch on the enum, not Yahoo's strings.

7. Today's opponent may be blank. Off-days, postponements, and doubleheaders all produce unusual opp_today values. Record exactly what Yahoo shows (@TEX, TEX, Off, PPD, DH1/DH2) — do not normalize away information the downstream lineup-optimizer needs.

8. Don't emit a signal with zero source URLs. If every page failed, write an empty-body signal with confidence: 0.0 and a prominent note to the coach: "Could not reach Yahoo — paste or retry required before any downstream agent runs."

Quick Reference

The five Yahoo URLs (from context/frameworks/data-sources.md):

Team:         https://baseball.fantasysports.yahoo.com/b1/23756/5
Standings:    https://baseball.fantasysports.yahoo.com/b1/23756?lhst=stand
Matchup:      https://baseball.fantasysports.yahoo.com/b1/23756/matchup
Transactions: https://baseball.fantasysports.yahoo.com/b1/23756/transactions
Free agents:  https://baseball.fantasysports.yahoo.com/b1/23756/players?status=A

Chrome tool order (load via ToolSearch first, then call):

1. mcp__claude-in-chrome__tabs_context_mcp    (confirm active tab, auth state)
2. mcp__claude-in-chrome__navigate            (go to URL)
3. mcp__claude-in-chrome__get_page_text       (extract DOM text)
4. mcp__claude-in-chrome__read_page           (structured read if text fails)

Roster slot order (for team-profile YAML; matches league-config.md):

C, 1B, 2B, 3B, SS, OF, OF, OF, UTIL, UTIL, SP, SP, SP, RP, RP, P, P, P, P, P, BN, BN, BN, IL, IL, IL

Status enum mapping:

Signal frontmatter (minimum fields):

---
type: league-state
date: 2026-04-17
emitted_by: mlb-league-state-reader
variant_synthesis: false
confidence: 0.9
source_urls:
  - https://baseball.fantasysports.yahoo.com/b1/23756/5
  - https://baseball.fantasysports.yahoo.com/b1/23756?lhst=stand
  - https://baseball.fantasysports.yahoo.com/b1/23756/matchup
  - https://baseball.fantasysports.yahoo.com/b1/23756/transactions
  - https://baseball.fantasysports.yahoo.com/b1/23756/players?status=A
---

Key resources:

• resources/template.md: team-profile.md output format, signal file output format, roster YAML schema, free-agents table schema
• resources/methodology.md: Yahoo navigation sequence, parsing patterns per page, FAAB reconstruction, paste parsing, degraded-mode prompts
• resources/evaluators/rubric_mlb_league_state_reader.json: 8 scoring criteria (roster completeness, FAAB accuracy, URL citation, fallback handling, etc.)

Inputs required:

• Authenticated Yahoo Fantasy session in Chrome (user's responsibility)
• context/league-config.md (league ID, team ID, roster shape)
• context/team-profile.md (prior state, may be stub)

Outputs produced:

• Updated context/team-profile.md (overwrite; reflects today's state)
• signals/YYYY-MM-DD-league-state.md (with frontmatter + source_urls)
• Degraded-mode prompts to user if any page fails