DeepSeek Harness Plan Mode: Plan Or Execute?

The first decision is not whether Plan Mode sounds safer. The first decision is whether a mistaken action can be isolated and undone without reconstructing the repository from memory.

Direct execution is usually suitable when all of the following are true:

• The change is limited to one file or one tightly bounded module.
• The expected behavior is already understood.
• A working test, lint, build, or type-check command exists.
• The working tree is clean or its existing changes are explicitly recorded.
• The change does not touch credentials, production configuration, access control, migrations, or deployment scripts.
• A reviewer can inspect the diff quickly and revert it without coordinating several owners.

A code refactoring task should normally begin in Plan Mode when any of these conditions apply:

• The change crosses multiple directories or modifies a shared interface.
• The repository has unfamiliar entry points, generated files, or indirect build scripts.
• The change affects authentication, billing, data migration, network access, or release automation.
• The expected rollback requires more than reverting one isolated commit.
• The acceptance test is still a hypothesis rather than a known command.
• Another person must approve the design before implementation begins.

Attention: Plan Mode is a workflow state, not a guarantee that every tool is harmless. Its actual write boundary depends on the current implementation, configuration, session state, and permission policy.

A useful rule is simple: if the cost of explaining the intended change is lower than the cost of repairing an incorrect change, planning is the cheaper option.

When a developer first opens a repository, the largest risk is not that the agent cannot produce a plan. The risk is that the plan is based on the wrong repository structure.

Before asking for implementation, establish a read-only baseline:

1. Identify the repository root. Confirm the active directory, repository metadata, and the branch or revision under review.
2. Locate the real entry point. Check the application launcher, package manifest, service bootstrap, or build target instead of assuming the first matching file is authoritative.
3. Trace dependencies. Find the modules that call the target code, the interfaces it implements, and the tests that exercise the behavior.
4. Record validation commands. Capture the exact commands used for unit tests, integration tests, linting, type checks, packaging, and smoke validation.
5. Inspect local changes. Confirm whether the working tree contains uncommitted edits, generated output, ignored files, or temporary patches.
6. Define exclusions. State which directories, secrets, deployment files, and unrelated modules are outside the task.
7. Save the evidence. Keep the revision, file list, dependency notes, and validation commands beside the plan.

This distinction matters because a plan is not the same as execution permission. A plan can describe intended file changes while the agent still lacks authority to write them. Conversely, a session with broad workspace permissions may be able to write even when the person reviewing the text assumes the system is still in a read-only phase.

The handoff should therefore contain evidence, not only prose. A reliable package includes:

• The starting commit or revision.
• The current branch and worktree status.
• Files inspected and files proposed for modification.
• The dependency path that justifies each change.
• The expected tests and their known baseline.
• The permission scope required for the next phase.
• The owner who can approve execution.

The official repository is the source of truth for the current implementation. Avoid relying on screenshots, remembered commands, or third-party claims about a default Plan Mode behavior that the current source does not confirm. The official README identifies the project as a rapidly changing developer preview, so local verification is part of the operating procedure rather than optional documentation work.

Teams usually need more than a binary answer. In practice, there are three workable patterns: direct execution, planning followed by execution, and a two-stage workflow with separate environments or approvals.

The right choice depends on four variables: impact range, rollback difficulty, repository familiarity, and approval responsibility. A team should not force every task into the same mode because the resulting policy will either slow down simple work or under-control risky work.

The table is a starting point, not a replacement for judgment. For example, a one-file change to an access-control rule may still require planning because the file count is small while the impact is large.

Use the following branch rules as the team default:

• If the task changes one isolated file, has a known validation command, and can be reverted with one clear action, choose direct execution.
• If the repository is unfamiliar or the agent cannot identify the entry point, dependency path, and validation command, choose Plan Mode first.
• If the task changes shared interfaces, database behavior, authentication, deployment, or generated artifacts, choose Plan Mode first, even if the patch appears short.
• If a second person must approve the design or write access, stay in Plan Mode until the task contract is accepted.
• If the plan is based on a different branch, commit, dependency lockfile, or generated state than the execution workspace, return to planning and refresh the evidence.
• If the remote session was disconnected or the host was restarted, do not resume execution automatically; recheck the revision, branch, worktree, dependencies, permissions, and running processes.
• If the plan is too detailed to review efficiently, compress it into decisions, affected surfaces, exclusions, tests, and rollback steps.
• If the plan is too vague to assign responsibility, remain in Plan Mode and require file-level or module-level scope.

The exit condition should be a task contract, not a fixed number of planning steps. Planning ends when another person can understand what will change, why it will change, how it will be tested, and what happens if the change fails.

For a maintenance task in an unfamiliar repository, the safest sequence is not “ask for a plan, then trust it.” The safer sequence is:

1. Create or select a clean working directory.
2. Capture the active revision, branch, and worktree status.
3. Search for package manifests, application entry points, test configuration, and CI definitions.
4. Follow imports, service registration, or route declarations to the target behavior.
5. Run the narrowest existing validation command without modifying source files.
6. Ask DeepSeek Harness to produce a plan that cites the discovered paths and commands.
7. Compare the plan against the repository evidence.
8. Approve only the files and commands that match the task contract.
9. Switch to execution with the smallest additional permission scope.
10. Review the diff before running broader tests or packaging steps.

This process exposes three common hidden costs:

• Dependency cost: a local-looking function may be called by several services or generated clients.
• Validation cost: a change may compile but fail a fixture, migration, snapshot, or integration check.
• Ownership cost: the person who understands the code may not be the person authorized to approve a write or deployment action.

A plan should also identify what it does not know. “The entry point was not confirmed” is more useful than a confident but unsupported assumption. If the agent cannot find a reliable test command, the correct result is not immediate execution; it is a request for a human-defined acceptance test.

High-risk projects should treat planning and execution as different security zones.

During planning, provide only the read access needed to inspect source, manifests, tests, and non-sensitive documentation. Do not expose production credentials merely because the agent may eventually need them. Do not place deployment tokens, private keys, customer exports, or unrestricted environment files inside the discovery scope.

During execution:

• Grant write access only to the approved worktree or branch.
• Exclude credential stores and unrelated repositories.
• Require explicit approval for network calls, deployment commands, migrations, and destructive shell operations.
• Preserve a record of the permission change.
• Revoke temporary access after validation or handoff.
• Keep production configuration separate from the development workspace whenever possible.

The official project materials confirm that Plan Mode exists as a state in the current code and persisted event model, but they do not justify assuming that enabling it automatically creates a complete security boundary. The current source tree and configuration area should be checked for the exact behavior used by the installed revision.

Reminder: A read-only plan can still reveal sensitive source, and a persisted session can still retain sensitive context. Data exposure and write authorization are separate controls.

A remote Mac is useful for long-running repository work, but a disconnected session can leave the plan and workspace out of sync.

A session interruption may occur after the plan was generated but before the branch was created, after a partial edit, during dependency installation, or while tests were still running. A restarted host may also restore the terminal session without restoring every process, environment variable, mounted volume, credential agent, or uncommitted file.

Before resuming, complete this recovery sequence:

1. Confirm the host identity and working directory.
2. Confirm the branch and starting revision recorded in the plan.
3. Inspect the worktree for partial edits, unexpected generated files, and merge markers.
4. Check whether dependency files or lockfiles changed.
5. Verify that required services, simulators, build tools, and test processes are available.
6. Recheck workspace permissions instead of assuming the previous permission state survived.
7. Compare the current file set with the plan.
8. Re-run the narrowest baseline validation.
9. Decide whether the plan remains valid or must be regenerated.
10. Continue only after the reviewer records the recovery decision.

A resumed session is not automatically an intact execution environment. This is especially important when a team hands the task from one operator to another. The new operator needs the plan, revision, permission record, current diff, test output, and unresolved questions—not just the conversation history.

For teams that need a stable remote Mac for this handoff, the NUKCLOUD remote Mac service can be evaluated as an execution environment, but the same recovery controls still apply. Remote availability does not remove the need for branch checks, workspace verification, and explicit approval.

A plan is ready for execution only when it produces these five artifacts:

1. Scope: files, modules, interfaces, and exclusions.
2. State: branch, commit, worktree condition, and dependency revision.
3. Authority: reviewer, write approver, test owner, and rollback owner.
4. Validation: exact commands, expected results, and acceptable exceptions.
5. Recovery: what to revert, where to restore from, and when to stop.

The transition itself should be deliberate:

• Freeze the plan against a specific revision.
• Ask the reviewer to approve the task contract.
• Create or select the approved worktree.
• Grant the minimum write permissions needed.
• Execute one bounded change at a time.
• Inspect the diff before expanding scope.
• Run the agreed validation command.
• Record failures rather than allowing the agent to silently broaden the task.
• Replan if the repository state changes materially.

For independent developers, the reviewer and executor may be the same person, but the evidence still matters. For a team, separating those roles prevents an agent from turning an informal suggestion into an unreviewed implementation. For a security-sensitive project, the approval record should survive the session so another operator can understand why access was granted.

Can DeepSeek Harness Plan Mode change files by itself?

Do not treat a generated plan as proof that the workspace is unchanged. The official project confirms a Plan Mode state in its code and persisted events, but the exact interface entry point and permission behavior may change during the developer preview. Before trusting the boundary, inspect the current release, source, and local permission configuration, then verify the working tree before execution.

Which coding tasks should start in Plan Mode?

Start with planning when the task crosses directories, changes public interfaces, touches authentication or deployment logic, depends on an unfamiliar repository, or has an expensive rollback. Direct execution is reasonable for a small, reversible edit with a known test command, a clean working tree, and no sensitive credentials in scope.

How should a team move from Plan Mode to execution?

Convert the plan into a task contract before granting write access. The contract should name the target branch and commit, files or modules in scope, expected behavior, excluded areas, validation commands, approval owner, and rollback action. Execution begins only after the reviewer accepts that contract and the workspace still matches the evidence used to create it.

Is Plan Mode safer for remote sessions?

It can reduce accidental writes during repository discovery, but remote execution adds separate failure modes. A disconnected session, restarted machine, changed branch, or refreshed dependency state can make the plan stale. Plan Mode is therefore not a substitute for isolation; verify the workspace, permissions, credentials, process state, and recovery path before continuing.

A sensible default is not “always plan” or “always execute.” It is a switching policy:

• Direct execution for bounded maintenance with immediate rollback and known tests.
• Plan Mode first for unfamiliar repositories, cross-module changes, uncertain validation, or approval-sensitive work.
• Two-stage execution when source access, credentials, production configuration, or team responsibility must be separated.

The policy should also define the trigger for switching back to planning. Examples include a new affected module, an unexpected generated file, a changed lockfile, a failed baseline test, a request to access credentials, or a remote session restart.

The current setup is often less reliable than it appears. A local laptop can sleep during a long task, leave the agent dependent on one person's terminal, and mix source changes with personal credentials. A generic shared environment can hide branch ownership, preserve stale dependencies, or make it unclear who approved a write. A manually maintained remote host can also lose process state after a restart and provide no consistent recovery record.

A dedicated remote Mac through NUKCLOUD can be a better fit when the task needs a persistent Apple environment, repeatable access, and a clean handoff between planning and execution. It is not automatically the best choice for every workload: a long-term heavy workload may justify owning a machine, and a task requiring direct physical hardware may not fit remote access. For temporary development, testing, or controlled execution, the NUKCLOUD Mac ordering page gives the team a way to evaluate the environment without first committing to permanent hardware.

Before starting a complex task, the final decision should look like this:

If the current setup cannot keep the revision, permissions, worktree, and validation result aligned, changing the model is not the first fix. Change the operating environment and handoff process first, then decide whether the next task should execute directly or pass through Plan Mode.