Default Symphony concurrency to five workers

[tianheil3]

Context

The out-of-the-box global concurrency default is currently ten agents, which is higher than the desired default operating posture for normal Symphony runs.

TL;DR

Default standard Symphony concurrency to five agents while keeping conservative onboarding profiles at one.

Summary

• Lowered the runtime agent.max_concurrent_agents default from 10 to 5.
• Updated generated custom and symphony-dev workflow defaults to emit five agents.
• Updated the repo workflow, SPEC, test fixture defaults, and dashboard snapshots to show /5.

Alternatives

• Change only elixir/WORKFLOW.md; rejected because generated workflows and omitted config would still use ten.
• Change starter and review-gated profiles to five; rejected because those profiles are intentionally conservative.

Test Plan

• make -C elixir all
• mix test test/symphony_elixir/workspace_and_config_test.exs:722 test/symphony_elixir/installer_apply_test.exs:45
• UPDATE_SNAPSHOTS=1 mix test test/symphony_elixir/status_dashboard_snapshot_test.exs

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 2acfff97-67df-4d88-b062-440630fd5bef

📥 Commits

Reviewing files that changed from the base of the PR and between c23d794 and 7d5271a.

📒 Files selected for processing (1)

• SPEC.md

📝 Walkthrough

Walkthrough

The default maximum concurrent agents limit is reduced from 10 to 5 across the codebase, including configuration schemas, workflow profiles, documentation, and corresponding test fixtures and expectations.

Changes

Cohort / File(s)	Summary
Configuration & Schema SPEC.md, elixir/lib/symphony_elixir/config/schema.ex, elixir/lib/symphony_elixir/installer/workflow_profile.ex	Default agent.max_concurrent_agents value reduced from 10 to 5 in schema, core config documentation, and profile defaults for "symphony-dev" and catch-all profiles.
Workflow Documentation elixir/WORKFLOW.md	Workflow configuration default updated from 10 to 5 agents.
Test Fixtures elixir/test/fixtures/status_dashboard_snapshots/*	Agent capacity displays updated across all snapshot files (evidence.md and snapshot.txt pairs) from X/10 to X/5 format.
Test Updates elixir/test/support/test_support.exs, elixir/test/symphony_elixir/workspace_and_config_test.exs, elixir/test/symphony_elixir/installer_apply_test.exs	Test defaults and assertions updated to expect agent.max_concurrent_agents: 5 instead of 10.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 Hop, hop, hooray! A change so clean and true,
Concurrency limits trimmed from ten to five—
The agents work with purpose, lean and light,
Resources dance with newfound grace and might,
Five's the magic number, tried and bright! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely describes the main change: reducing the default Symphony concurrency from 10 to 5 workers.
Description check	✅ Passed	The description fully completes the required template with clear context, a concise TL;DR, detailed summary bullets, considered alternatives with justifications, and comprehensive test plan evidence.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/default-concurrency-five

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@SPEC.md`:
- Line 586: The SPEC currently has conflicting defaults for
agent.max_concurrent_agents (Line 586 shows default 5 while Section 5.3.5 shows
default 10); update the document so both occurrences state the same default
value—pick the correct intended default (e.g., 10 or 5) and change the other
occurrence to match; search for the symbol "agent.max_concurrent_agents" and
edit every mention (including the entry at Line 586 and the Section 5.3.5
description) so the default value is consistent across the SPEC.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 8a1a6d30-5c59-4a64-82ac-1436b48f90b0

📥 Commits

Reviewing files that changed from the base of the PR and between 6ecf9a4 and c23d794.

📒 Files selected for processing (17)

• SPEC.md
• elixir/WORKFLOW.md
• elixir/lib/symphony_elixir/config/schema.ex
• elixir/lib/symphony_elixir/installer/workflow_profile.ex
• elixir/test/fixtures/status_dashboard_snapshots/backoff_queue.evidence.md
• elixir/test/fixtures/status_dashboard_snapshots/backoff_queue.snapshot.txt
• elixir/test/fixtures/status_dashboard_snapshots/credits_unlimited.evidence.md
• elixir/test/fixtures/status_dashboard_snapshots/credits_unlimited.snapshot.txt
• elixir/test/fixtures/status_dashboard_snapshots/idle.evidence.md
• elixir/test/fixtures/status_dashboard_snapshots/idle.snapshot.txt
• elixir/test/fixtures/status_dashboard_snapshots/idle_with_dashboard_url.evidence.md
• elixir/test/fixtures/status_dashboard_snapshots/idle_with_dashboard_url.snapshot.txt
• elixir/test/fixtures/status_dashboard_snapshots/super_busy.evidence.md
• elixir/test/fixtures/status_dashboard_snapshots/super_busy.snapshot.txt
• elixir/test/support/test_support.exs
• elixir/test/symphony_elixir/installer_apply_test.exs
• elixir/test/symphony_elixir/workspace_and_config_test.exs

[tianheil3]

[codex] Changes since last review:

• Updated the second SPEC.md concurrency default mention to 5 so the config contract is consistent.
  Commit: 7d5271a
  Tests: rg for stale SPEC default-10 mentions.