feat: add subAgentsTemperature config for per-agent temperature tuning

[avoidwork]

Description

Add a subAgentsTemperature config section that allows per-agent temperature tuning for sub-agents. This enables fine-grained control over agent behavior by setting temperature values per agent type via config.yaml or environment variables.

Changes:

• New Zod schema SubAgentsTemperatureSchema validating agent name → temperature (0-2) mappings
• Schema added to root ConfigSchema in src/config/config.js
• Accessor function getSubAgentTemperature(agentName) for reading per-agent temperature
• Environment variable resolution support (e.g., SUB_AGENTS_TEMPERATURE_CODING=0.3)
• Hyphen-to-underscore conversion for agent names with hyphens (e.g., code-review → CODE_REVIEW)
• Per-agent model instances created in deepAgents.js with configured temperature
• Full test coverage for schema validation, env var resolution, and accessor function

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor (no functional changes)
• Performance improvement
• CI / build / tooling

Testing

• Schema validation: Valid temperatures (0-2), invalid temperatures (out of range, non-numeric), empty config
• Env var resolution: SUB_AGENTS_TEMPERATURE_CODING=0.3 correctly populates subAgentsTemperature.coding
• Hyphenated agent names: SUB_AGENTS_TEMPERATURE_CODE_REVIEW=0.1 correctly populates subAgentsTemperature['code-review']
• Accessor function: Correct value returned for listed agents, undefined for unlisted agents and empty strings
• All existing tests pass (1192 tests)
• Lint passes with no warnings or errors

Coverage

• Line coverage maintained

Checklist

• npm run lint passes
• Tests pass with maintained line coverage
• No forbidden patterns used
• Conventional Commit style applied

Closes #843

[avoidwork]

Implementation Audit Results

Goal Fulfillment

Goal	Status	Notes
Add subAgentsTemperature config section	✅ Complete	New schema file created, added to ConfigSchema
Zod schema validation (0-2 range)	✅ Complete	SubAgentsTemperatureSchema validates record of agent→temp
Environment variable resolution	✅ Complete	DROPPED_KEYS updated, hyphen handling added to _toUpperSnake
Accessor function getSubAgentTemperature	✅ Complete	Returns configured value or undefined for unlisted agents
Wire into deepAgents sub-agent model creation	✅ Complete	Per-agent model instances created with configured temperature

Spec Compliance

config-system spec:

• ✅ Configuration loading and validation - subAgentsTemperature section added to ConfigSchema with Zod validation
• ✅ subAgentsTemperature defaults to empty object {}
• ✅ Invalid values rejected (out of range, non-numeric)

sub-agents-temperature spec:

• ✅ Schema validates valid temperatures (0-2), rejects out-of-range and non-numeric
• ✅ Empty config accepted
• ✅ Environment variable resolution: SUB_AGENTS_TEMPERATURE_CODING=0.3 → subAgentsTemperature.coding
• ✅ Hyphenated agent names: SUB_AGENTS_TEMPERATURE_CODE_REVIEW → subAgentsTemperature['code-review']
• ✅ Accessor function returns correct values, undefined for missing/empty agents

subagent spec:

• ✅ Sub-agent model created with per-agent temperature from config
• ✅ Agents not in config use provider default (undefined temperature)

Task Completion

All 18 tasks from tasks.md completed:

• Task 1.1-1.2: Schema creation and export ✅
• Task 2.1-2.3: ConfigSchema addition and accessor ✅
• Task 3.1-3.2: DROPPED_KEYS and hyphen handling ✅
• Task 4.1-4.3: deepAgents wiring ✅
• Task 5.1-5.4: Unit tests ✅
• Task 6.1-6.4: Verification (tests pass, lint passes, app starts) ✅

Quality Check

• Tests: 1192/1192 passing (0 failures)
• Lint: 0 warnings, 0 errors
• Formatting: All files formatted with oxfmt
• No regressions: All existing tests continue to pass
• Clean implementation: Minimal changes, follows existing patterns

Code Changes Summary

File	Changes	Purpose
src/config/schemas/subAgentsTemperature.js	New file	Zod schema for subAgentsTemperature
src/config/schemas/index.js	+1 line	Export new schema
src/config/config.js	+34 lines	Add to ConfigSchema, add accessor, _setResolvedConfig
src/config/loader.js	+7 lines	Add to DROPPED_KEYS, hyphen handling, _setResolvedConfig call
src/agent/deepAgents.js	+23/-1 lines	Per-agent model instances with temperature
tests/unit/config-subAgentsTemperature.test.js	New file	217 lines of comprehensive tests