Devin SWE-2 harness

This page is the canonical operator guide for the built-in devin provider, centered on the logical swe-2 model. Use /login devin for the Devin CLI subscription PKCE flow or DEVIN_API_KEY for an already-owned CLI session token. A user-local ~/.omk/agent/devin.md may add operator notes, but it is not the portable product contract.

Authentication, transport, and verification limits are owned by Providers; this page covers how OMK drives SWE-2 as a harness.

Presets

Project presets live in .omk/presets.json (or ~/.omk/agent/presets.json) and are consumed by the preset extension from packages/coding-agent/examples/extensions/preset.ts. The shared SWE-2 presets intentionally omit the tools key so role/domain lane grants keep control of the active tools.

Preset	Provider	Model	Thinking	Use
swe2-verified	devin	swe-2	high	Default SWE-2 coding baseline: multi-file edits with tests.
swe2-max	devin	swe-2	max	Long-horizon, uncertain, or repository-wide work that should use the 1M budget.
swe2-fast-edit	devin	swe-2	medium	Small, well-specified edits where medium acts sooner and costs less.

{
  "swe2-verified": { "provider": "devin", "model": "swe-2", "thinkingLevel": "high" },
  "swe2-max": { "provider": "devin", "model": "swe-2", "thinkingLevel": "max" },
  "swe2-fast-edit": { "provider": "devin", "model": "swe-2", "thinkingLevel": "medium" }
}

For a new session without presets:

omk --provider devin --model swe-2 --thinking max

Effort tiers

SWE-2 exposes exactly three server-declared efforts. OMK maps its thinking tiers as follows and rejects anything else before sending credentials; max is a reasoning level, not the Devin Max subscription tier.

OMK tier	swe-2
off, minimal, low	unavailable
medium	medium
high	high
xhigh, ultra	unavailable
max	max

Guidance from the SWE-2 announcement: medium makes its first real edit sooner and is the cost-efficient choice for simple and intermediate tasks; high and max plan more, explore more of the codebase, and verify more on complex tasks. recommendedDevinEffortForIntent() encodes the same split (code → medium, test → high, debug/repo → max).

Context budget: 1,000,000 tokens

devin/swe-2 ships with contextWindow: 1000000 and maxTokens: 16384. These are local budgets that drive OMK's context budgeting and compaction, not published SWE-2 limits; Cognition has not published a context window for SWE-2. Chat completion settings follow the captured native Devin CLI 3000.6.2 defaults (maxNewlines 400, empty stop list). topP=0.95 is protobuf field 8; field 6 is firstTemperature and is omitted. This removes the old 200-newline cap and synthetic stops, but does not prove that every interrupted reply had that cause. The budget also selects the catalog lane:

1. Before each turn OMK reads GetCliModelConfigs. SWE-2 family entries may carry a 1M Context axis (order 1) beside the effort axis. A local budget of 1,000,000 or more asks for that 1M-context lane; below it, the standard lane is used and 1M entries are ignored.
2. A catalog with no 1M-context lane keeps the standard lane for the selected effort.
3. If the chosen lane declares a context window smaller than the local budget, the request fails with ... declares a N-token context window; lower the models.json contextWindow before retrying. OMK never shrinks the budget silently, never invents a wire UID, and never downgrades to another effort.
4. Fast-lane (Fast Mode) entries are excluded from effort routing and are reachable only through their own UID models (ids ending in -fast or -priority). Output is capped against the authenticated catalog's declared maximum.

To lower the budget (for example if your account only serves the standard lane at 262,144 tokens), override the built-in model in ~/.omk/agent/models.json:

{
  "providers": {
    "devin": {
      "modelOverrides": {
        "swe-2": { "contextWindow": 262144 }
      }
    }
  }
}

Recommended compaction settings for 1M sessions keep the defaults but raise the recent-token window so summaries do not discard the working set:

{
  "compaction": { "enabled": true, "reserveTokens": 16384, "keepRecentTokens": 60000, "maxUsageRatio": 0.85 }
}

Context discipline still applies: the budget is room for the repository, not an invitation to dump it. Prefer targeted reads and searches, keep tool output bounded, and let precompact-checkpoint snapshot state before compaction rather than restarting sessions. Quota is per account; a larger window consumes more of it per turn.

With a Devin credential configured, the status rail's USAGE section shows the account's daily and weekly quota meters from GetUserStatus (or the plan name and credit balances when the plan reports no quota windows), matching the CLI's /usage surface.

Domain routing

Selecting the devin provider auto-applies the devin-harness loadout by default; this does not require OMK_DOMAIN_ROUTING=1. Set OMK_DEVIN_HARNESS=0 to disable that provider-specific dispatch. The flag is independent from OMK_GROK_HARNESS.

Loadout policies reject extension tools that shadow builtins fail-closed. A host that intentionally replaces the builtin bash (for example a Landstrip shell provider) should keep OMK_DEVIN_HARNESS=0 in its launcher until the replacement is removed or bridged; the devin.md overlay and the model budget still apply in that case.

General prompt-based domain routing is separate and opt-in through OMK_DOMAIN_ROUTING=1. It selects one of the profiles under loadout-domains/ and composes it with the active role loadout. SWE-2 presets only set provider, model, thinking level, and instruction pointers.

Model selection

The devin catalog leads with the logical swe-2 model; the server's SWE-2 family metadata supplies each effort's wire UID at request time. Every other lane the account catalog advertises is its own logical model whose id is the wire UID — for example devin/claude-opus-5-high, devin/gpt-5-6-sol-xhigh, devin/gemini-3-8-flash-medium, devin/kimi-k3-max, devin/glm-5-3-high, devin/grok-4-6-xhigh, devin/deepseek-v4-pro-max, devin/swe-1-7, or devin/inkling-max. Flat models pin their declared effort lane, so /think levels are fixed per model and No Thinking/None lanes report reasoning: false. Availability is account- and plan-dependent: a lane absent from your catalog fails loudly instead of being remapped. Use /model or omk --list-models devin for the current list. Image input is unsupported; provide text.

Skill and MCP matrix summary

Use the normal OMK lane grant model: grant the smallest skill and MCP surface that matches the task.

For each non-queued devin request started through AgentSession.prompt(), OMK calls selectDevinHarnessSkills() against the live discovered skill descriptions after ordinary prompt-template expansion. It merges up to three matches with explicit/settings selections and rebuilds that turn's <active_skills source="devin-harness"> marker. The scorer is the same selectSkills() used by the Grok harness: weak 0.35 / strong 0.7 thresholds, deterministic input-order ties, first-name-wins deduplication, explicit-only skills never auto-selected, and headroom only for lexical pressure cues or the session's measured context-pressure bucket. A task with no signals yields an empty automatic grant rather than the full allowlist. Queued steer, followUp, or prompt(..., { streamingBehavior }) messages retain the active run's system prompt.

Task class	Skills	MCP
Multi-package or repo-context work	packages; add headroom only under context pressure	none by default
Repo graph or broad comprehension	understand-anything; optionally packages	understand-anything
TypeScript/Rust/Python/Go edits	programming; add lsp or ast-grep only for symbol/structural work	none by default
New behavior or bug fix with regression test	tdd-workflow, programming	none by default
Runtime failures or broken behavior	debugging	task-specific only
Library API lookup	task skill as needed	context7
Current public URL or docs lookup	task skill as needed	fetch
UI/TUI verification	task skill as needed	playwright only when browser/UI evidence is required

Relevant evidence hooks for SWE-2 lanes are pre-shell-guard, protect-secrets, typecheck-after-edit, stop-verify, session-context, and precompact-checkpoint. Hook output is incremental evidence; code changes still need the project's required final verification command before claiming type/lint cleanliness.

Suggested TUI flow

1. Run /login devin once; the account picker stores the CLI session token in auth.json.
2. Select /preset swe2-verified for normal coding work, /preset swe2-max for long-horizon or repository-wide tasks, and /preset swe2-fast-edit for small edits.
3. Use /think medium, /think high, or /think max to change effort mid-session; other levels are rejected.
4. If a turn fails with an "unavailable or ambiguous" route or a smaller declared context window, treat it as a configuration signal: check devin models list, or lower contextWindow as shown above. Do not retry with a guessed wire UID.
5. Keep credentials out of preset JSON, prompts, and logs: the session token, the exchanged user JWT, and auth.json contents are secrets under protect-secrets.

Troubleshooting does not provide an export named

If Devin fails with The requested module './devin-connect.js' does not provide an export named 'MAX_FRAME_BYTES', the loaded stream module is mixed with an older unary module. That is a client load error, not an orphan tool call or a remote protocol trailer.

• Current OMK keeps the 16 MiB Connect frame cap inside devin-connect-stream.ts, so a stale devin-connect.js cannot fail that named import.
• /new does not reload already-imported provider modules. Quit and restart OMK after a rebuild.
• The failure banner should say to restart OMK, not to sanitize a sticky transcript.

Troubleshooting invalid_argument

A Connect invalid_argument trailer is a provider/request failure, not evidence of an orphan tool call or a safety refusal. Keep any reported trace ID for support; OMK includes only a bounded hexadecimal trace ID, never the remote error body.

• The SWE-2 adapter rejects zero, negative, and non-finite temperature values before sending credentials. A controlled high-effort probe returned invalid_argument at temperature: 0, while the default temperature completed the same prompt. Omit the option to use the native default of 1; OMK does not silently replace an explicit zero.
• Check model, effort, context budget, and request settings with /debug. Repair tool history only when a tool/message mismatch is actually identified.
• After updating or rebuilding the adapter, quit and restart the OMK process. /new replaces conversation state; it does not reload an imported provider module. This is an update-application step, not a guaranteed fix for every provider error.
• If a minimal tool-free request still fails at the default temperature, preserve the trace ID and investigate provider compatibility or availability rather than repeatedly sanitizing the same transcript.

Local overlay

When the devin provider is active, OMK appends ~/.omk/agent/devin.md (capped at 24,000 characters) to the system prompt, mirroring the Grok grok.md overlay. Treat that file as optional host configuration for effort defaults, compaction notes, or team conventions; this page and the current provider documentation remain authoritative and it cannot override higher-priority instructions.