Model Configuration

AgentSessionManager centralizes all model identifiers, default models, and per-token pricing in the AgentSessionManager.Models module. This guide explains how to inspect, override, and extend these settings.

Default Models

Each provider adapter has a default model that is used when no :model option is passed to start_link/1:

Querying the Default at Runtime

AgentSessionManager.Models.default_model(:claude)
# => "claude-haiku-4-5-20251001"

Overriding via Application Config

Add the following to your config/config.exs (or environment-specific config):

config :agent_session_manager, AgentSessionManager.Models,
  claude_default_model: "claude-sonnet-4-5-20250929"

This override takes effect at runtime without recompilation.

Overriding per Adapter Instance

Pass the :model option directly when starting an adapter:

{:ok, adapter} = ClaudeAdapter.start_link(model: "claude-opus-4-6")

This always takes precedence over the default.

Pricing Table

The Models module ships a built-in pricing table used by AgentSessionManager.Cost.CostCalculator for cost estimation.

Structure

The pricing table is a nested map keyed by provider name:

%{
  "claude" => %{
    default: %{input: 0.000003, output: 0.000015},
    models: %{
      "claude-opus-4-6" => %{
        input: 0.000015,
        output: 0.000075,
        cache_read: 0.0000015,
        cache_creation: 0.00001875
      },
      "claude-sonnet-4-5" => %{...},
      "claude-haiku-4-5" => %{...}
    }
  },
  "codex" => %{
    default: %{input: 0.000003, output: 0.000015},
    models: %{
      "o3"        => %{input: 0.000010, output: 0.000040},
      "o3-mini"   => %{input: 0.0000011, output: 0.0000044},
      "gpt-4o"    => %{input: 0.0000025, output: 0.000010},
      "gpt-4o-mini" => %{input: 0.00000015, output: 0.0000006}
    }
  },
  "amp" => %{
    default: %{input: 0.000003, output: 0.000015},
    models: %{}
  }
}

All rates are in USD per token.

Model Resolution

The cost calculator resolves rates in this order:

1. Exact match -- "claude-opus-4-6" matches the key directly.
2. Prefix match -- "claude-sonnet-4-5-20250929" matches the "claude-sonnet-4-5" prefix, allowing versioned model IDs to resolve without explicit entries for every date suffix.
3. Provider default -- if no model key matches, the provider's default rates are used.
4. Error -- if the provider is not in the table at all, {:error, :no_rates} is returned.

Overriding the Pricing Table

Replace the entire table via application config:

config :agent_session_manager, AgentSessionManager.Models,
  pricing_table: %{
    "claude" => %{
      default: %{input: 0.000003, output: 0.000015},
      models: %{
        "claude-opus-4-6" => %{input: 0.000020, output: 0.000080}
      }
    }
  }

Or pass a custom table directly to the cost calculator:

CostCalculator.calculate(tokens, "claude", "claude-opus-4-6", my_pricing_table)

Listing Known Models

AgentSessionManager.Models.model_names()
# => ["claude-haiku-4-5", "claude-opus-4-6", "claude-sonnet-4-5",
#     "gpt-4o", "gpt-4o-mini", "o3", "o3-mini"]

Reasoning Effort (Codex)

The Codex adapter extracts reasoning effort from CLI thread metadata at runtime. There is no hardcoded default -- the effort level is determined by the Codex CLI and reported in the run_started event:

%{
  type: :run_started,
  data: %{
    confirmed_reasoning_effort: "medium",
    confirmation_source: "codex_cli.thread_started"
  }
}

Pass a reasoning effort when starting the Codex adapter:

CodexAdapter.start_link(
  working_directory: "/my/project",
  sdk_opts: [reasoning_effort: :medium]
)

Thinking Mode (AMP)

The AMP adapter accepts a :thinking option that defaults to false:

AmpAdapter.start_link(thinking: true)

Updating Models and Prices

When provider APIs introduce new models or change pricing:

1. Edit lib/agent_session_manager/models.ex -- update @claude_default_model, add model entries to @default_pricing_table, etc.
2. Run mix test -- all tests reference the central Models module (or AgentSessionManager.Test.Models for test fixtures), so a single change propagates everywhere.
3. If you add a brand-new provider, add a default_model/1 clause and a new provider entry in the pricing table.

Test Fixtures

Test code uses AgentSessionManager.Test.Models (defined in test/support/test_models.ex) to centralize test fixture model strings:

AgentSessionManager.Test.Models.claude_model()        # => "claude-haiku-4-5-20251001"
AgentSessionManager.Test.Models.claude_sonnet_model()  # => "claude-sonnet-4-5-20250929"
AgentSessionManager.Test.Models.claude_opus_model()    # => "claude-opus-4-6"
AgentSessionManager.Test.Models.codex_model()          # => "gpt-5.3-codex"
AgentSessionManager.Test.Models.reasoning_effort_high()    # => "xhigh"
AgentSessionManager.Test.Models.reasoning_effort_medium()  # => :medium

Changing a model name in Test.Models updates every test that references it.