Built-in tools

Thirty-nine tools ship in internal/agent (thirty-seven always-on plus todo_write and exit_plan_mode). The model sees their JSON-schema parameters via the OpenAI tools API; the TUI renders each invocation as a bordered card with a verb-style header (see How tool calls render in the TUI). All paths are resolved against the agent’s working directory (absolute paths are also accepted).

In addition to the built-ins, MCP tools register dynamically when an [[mcp_servers]] block is present in ~/.yottacode/config.toml. They appear as mcp/<server>/<tool> and flow through the same approval modal and permission rules — see mcp.md and the MCP(...) rule shape in security-and-allow-lists.md. MCP tools default to approval-required unless the server explicitly hints them as read-only.

Tool	Approval	One-line summary
`read_file`	none	Read a text or image file (png/jpg/gif/webp) with optional line offset/limit
`read_many_files`	none	Read multiple UTF-8 files in one call
`write_file`	required	Overwrite or create a file
`edit_file`	required	Surgical `old_string`→`new_string` replacement
`apply_diff`	required	Apply a unified diff patch
`mkdir`	required	Create a directory and missing parents
`copy_file`	required	Copy a file to a new path
`move_file`	required	Move or rename a file or directory
`delete_file`	required	Delete a file or empty directory
`list_git_changed_files`	none	List changed files in the current repo
`git_branch_status`	none	Show branch/upstream/dirty state
`git_show_file_at_rev`	none	Read a file from a past revision
`git_diff_files`	none	Show a diff for refs and/or files
`git_stage_files`	required	Stage specific files or all changes
`git_unstage_files`	required	Unstage specific files
`git_create_branch`	required	Create and switch to a new branch
`git_commit`	required	Commit staged changes
`git_commit_context`	none	Typed snapshot for drafting a commit message (paired with `git_commit_apply`)
`git_commit_apply`	required	Validate a one-line subject and run `git commit` with structured result envelope
`gh_pr_context`	none	Typed snapshot for opening a PR (base resolution, ahead-count, push state, gh availability, PR template)
`gh_pr_create`	required	Validate title and open a PR via the `internal/github.Interface` adapter with typed result envelope
`gh_pr_read`	none	Fetch PR metadata only via one API call (use instead of `run_bash gh pr view --json …`)
`gh_pr_review_context`	none	Fetch PR metadata + diff + check rollup via the `internal/github.Interface` adapter for review
`gh_pr_update`	required	Rewrite an existing PR’s title and body via the `internal/github.Interface` adapter; title validation + non-empty-body guard
`gh_pr_add_comment`	required	Post a top-level conversation comment on a PR; body capped, approval-gated
`gh_issue_read`	none	Fetch issue metadata + comments (use instead of `run_bash gh issue view --json …`)
`gh_issue_list`	none	List open issues matching label/assignee/milestone filters
`git_push`	required	Push the current branch to origin with deterministic upstream detection; surfaces the PR URL when one exists
`git_log_file`	none	Show history for one file
`git_blame_lines`	none	Blame a line range in a file
`git_merge_base`	none	Find merge base between two refs
`git_checkpoint`	required	Create a local checkpoint commit
`rollback`	required	Reset the repo to an earlier commit
`run_tests`	none	Run the repo’s test command
`list_dir`	none	One-line-per-entry directory listing
`glob`	none	Doublestar pattern match
`grep`	none	Ripgrep (or GNU grep fallback)
`fetch_url`	none	Fetch a single HTTP(S) URL and return capped textual content
`run_bash`	required	Shell command via `/bin/sh -c`
`git`	varies	Unified git invocation; read-only auto-runs, mutations prompt
`todo_write`	none	Maintain the agent’s working task plan, rendered as a card
`exit_plan_mode`	required	Only callable in `/plan` mode; presents the plan for user approval
`Agent`	none	Dispatch a typed subagent that runs in its own context window; see subagents.md

“Approval = required” means the tool always pauses for a y / a / N from the user, unless an allow rule in <cwd>/.yottacode/permissions.json (or its gitignored .local.json sibling) matches the call, or --yolo is set (DANGEROUS). See architecture.md for the approval round-trip and the permissions schema.

How tool calls render in the TUI

Every tool call renders as a bordered card with three regions:

go test ./internal/tui/ -run TestDemo_CardOutput -v
go test ./internal/tui/ -run TestDemo_CardOutput -v | sed -n '/^─── /,/^--- PASS/p' | sed '/^--- PASS/d'

╭ Verb(arg)
│   <body lines, capped at 10>
╰ <summary footer>

The gutter glyphs (╭ │ ╰) render dim; the header is bold; the footer is dim, with exit 0 in green and exit N≠0 / ✗ <error> in bold red. Body rows are indented three columns under the gutter so the shape reads as “header, indented content, footer.”

Header verbs. The raw tool name still appears in the agent’s tool-call log; the TUI renames it for readability. Mapping:

Tool	Header
`run_bash`	`Bash(<command>)`
`read_file`	`Read(<path>)` or `Read(<path> @ L<offset>+<limit>)` (images: `Read(<path>)`)
`read_many_files`	`Read(N files)`
`write_file`	`Write(<path>)`
`edit_file`	`Edit(<path>, single\|all)`
`apply_diff`	`Patch(apply)`
`mkdir`	`Mkdir(<path>)`
`copy_file`	`Copy(<src> → <dst>)`
`move_file`	`Move(<src> → <dst>)`
`delete_file`	`Delete(<path>)`
`list_dir`	`List(<path>)`
`glob`	`Glob(<pattern>)` or `Glob(<pattern> in <root>)`
`grep`	`Grep("<pattern>" in <path>)`
`fetch_url`	`Fetch(<url>)`
`run_tests`	`Test(<command>)`
`rollback`	`Rollback(<target>)`
`git`	`Git(<subcommand> <args>)`
`git_branch_status`	`Git(branch status)`
`git_show_file_at_rev`	`Git(show <path> @ <rev>)`
`git_diff_files`	`Git(diff <base>..<head>)`
`git_stage_files` / `git_unstage_files`	`Git(stage N files)` or `Git(stage all)` / `Git(unstage N files)`
`git_create_branch`	`Git(create branch <name>)` or `Git(create branch <name> from <start_point>)`
`git_commit`	`Git(commit)`
`git_log_file`	`Git(log <path>)`
`git_blame_lines`	`Git(blame <path>:L<a>-L<b>)`
`git_merge_base`	`Git(merge-base <base>..<head>)`
`git_checkpoint`	`Git(checkpoint)`
`list_git_changed_files`	`Git(list changed)`

ASCII control characters inside an arg (a stray \n in a path, a tab in a filename, etc.) are stripped before the header renders, so a malformed arg can never break the card’s box shape. Long bash commands are clipped to fit the terminal width with a …) tail.

Body. Carries the tool’s interesting output: directory entries, grep matches, command stdout, diff hunks. Capped at 10 visible lines with a trailing …N more line(s) notice — the model still receives the full output via the agent’s tool-result event. A few tools have card-specific body shapes:

run_bash / run_tests / git split their output into stdout, a ── stderr ── separator, and stderr. The footer carries the process exit code (green when zero, red otherwise).
edit_file renders a syntax-highlighted - (red) / + (green) diff in the body instead of the textual confirmation.
git with a destructive flag (--force, --hard, -D, --delete, …) prepends a bold-red ⚠ DESTRUCTIVE FLAG(S): <flags> row to the body so it’s hard to y past by reflex.
fetch_url drops the raw HTTP body and shows only the response metadata (Status, Content-Type, optional truncation note). The footer reports the response body size. The model still receives the full content; the user is spared 64+ KiB of minified markup.
read_file / write_file show no body — the footer’s N lines · M bytes / wrote N bytes carries the entire signal.

Footer. Summarizes the call: N entries, wrote N bytes, N lines · M bytes [(truncated)], N matches, exit N (colored), or the tool’s confirmation message. When the call errored, the footer renders ╰ ✗ <error> in bold red and the body shows the raw error verbatim (per-tool body shaping is bypassed for errors).

read_file

Read a text or image file. For text files, output is cat -n style (1-indexed line numbers). For image files (.png, .jpg, .jpeg, .gif, .webp), the image data is returned as a native visual content block that vision-capable models can see directly.

Param	Type	Default	Notes
`path`	string	—	Absolute or cwd-relative
`offset`	int	`1`	1-indexed start line (text files only)
`limit`	int	`2000`	Max lines to return (text files only)

Image support. When the path points to a recognized image file and the provider supports images in tool results (currently Anthropic only), the tool reads the raw bytes (up to 20 MiB) and returns them as an image content block alongside a text label like [image: photo.png, image/png, 12345 bytes]. On providers that don’t support images in tool results, only the text label is returned. The same deny list applies to images.

No approval — the model legitimately needs to read dotfiles, USER.md, /etc/os-release, etc. A narrow deny list still applies: ~/.ssh, ~/.aws, ~/.gnupg, ~/.netrc, ~/.yottacode/.env, ~/.kube/config, ~/.docker/config.json, ~/.config/gh/hosts.yml, ~/.config/gcloud, <cwd>/.env, <cwd>/.env.local. Reading those returns an error — closes the silent prompt-injection exfiltration vector. Use run_bash (which prompts) if you really need them.

read_many_files

Read multiple UTF-8 text files in one call. Useful when the model needs context from a handful of related files without paying for many separate round-trips.

Param	Type	Default	Notes
`paths`	[]string	—	Required; max 20 files
`offset`	int	`0`	Bytes; negatives clamped to 0
`limit`	int	`524288`	Per-file cap

Returns sections in the form:

==> path/to/file <==
<content>

Each file gets its own [truncated] marker if needed.

write_file

Full overwrite. Creates parent directories as needed.

Param	Type	Default	Notes
`path`	string	—	Absolute or cwd-relative
`content`	string	—	Full new file contents

Always prompts for approval. The preview shows the path and a 200-char content snippet.

edit_file

Surgical string replacement. Fails when old_string matches zero or more-than-one place (uniqueness check), unless replace_all=true.

Param	Type	Default	Notes
`path`	string	—	Must exist
`old_string`	string	—	Must be non-empty and != `new_string`
`new_string`	string	—	The replacement
`replace_all`	bool	`false`	Disable uniqueness check

Always prompts for approval. The TUI’s approval modal renders a colored diff (red − / green +) so you see exactly what’s about to change.

apply_diff

Apply a unified diff patch using git apply. This is better than edit_file for multi-hunk changes across one or more files.

Param	Type	Default
`diff`	string	—

Always prompts for approval. The diff header is parsed and each touched file is run through the same write-path validator write_file / edit_file use — yottacode-managed state, .git internals, paths outside cwd, and symlinks are refused before git apply runs. A Deny(Edit(<pattern>)) rule applies if any target path matches; an Allow(Edit(<pattern>)) rule auto-approves only when every target path matches (mixed-path diffs still prompt).

mkdir

Create a directory and any missing parents.

Param	Type	Default
`path`	string	—

Always prompts for approval.

copy_file

Copy a file from src to dst. Creates destination parent directories if needed.

Param	Type	Default
`src`	string	—
`dst`	string	—

Always prompts for approval.

move_file

Move or rename a file or directory. Creates destination parent directories if needed.

Param	Type	Default
`src`	string	—
`dst`	string	—

Always prompts for approval.

delete_file

Delete a file or an empty directory.

Param	Type	Default
`path`	string	—

Always prompts for approval.

list_git_changed_files

List changed files in the current git repo, combining staged, unstaged, and optionally untracked files.

Param	Type	Default
`staged`	bool	`true`
`unstaged`	bool	`true`
`untracked`	bool	`true`

No approval.

git_branch_status

Show the current branch, upstream, ahead/behind counts, and whether the working tree is dirty.

This is a compact status helper for coding sessions where the model wants repo state without parsing full git status output.

No parameters. No approval.

git_show_file_at_rev

Read a file from a specific git revision without changing the working tree. Useful for regressions, comparisons, and historical inspection.

Param	Type	Default
`path`	string	—
`rev`	string	`HEAD`

No approval.

git_diff_files

Show a diff for specific refs and/or file paths.

Param	Type	Default	Notes
`base`	string	current working tree	Optional base revision
`head`	string	—	Optional head revision
`paths`	[]string	—	Restrict diff to one or more files

Examples:

diff current working tree: omit both base and head
diff one revision vs working tree: set base
diff two revisions: set both base and head

No approval.

git_stage_files

Stage specific files (git add -- ...) or all changes (git add -A).

Param	Type	Default	Description
`paths`	[]string	—	Paths to stage. Mutually exclusive with `all`.
`all`	bool	`false`	Stage all tracked, untracked, and deleted files (`git add -A`). Mutually exclusive with `paths`.

Provide either paths or all, not both. Returns staged N file(s) for path mode or staged all changes for the bulk mode.

Always prompts for approval.

git_unstage_files

Unstage specific files with git reset HEAD -- ....

Param	Type	Default
`paths`	[]string	—

Always prompts for approval.

git_create_branch

Create a new local branch and switch HEAD to it (git switch -c <name> [<start_point>]). The branch name is validated via git check-ref-format --branch before any switch happens, and the tool refuses with a branch_exists error if a local branch by that name already exists — it never overwrites or fast-forwards. The working tree is left as-is (no precheck against dirty state); git itself will refuse the switch if local changes would be clobbered.

Param	Type	Default	Description
`name`	string	—	Branch name to create (required).
`start_point`	string	`HEAD`	Optional starting ref (commit / branch / tag).

Returns created=true branch=<name> from=<short_sha> on success.

Always prompts for approval.

git_commit

Create a commit from the currently staged changes.

Param	Type	Default
`message`	string	—

Always prompts for approval.

git_commit_context

Composite read-only snapshot used to draft a one-line commit message without parsing bash heredoc output. Returns labeled sections under ## state, ## staged.name-status, ## staged.diff, ## recent.subjects, ## branch.commits, ## prose, ## unstaged, and ## untracked. The ## state block carries the deterministic staged_empty=, detected_style= (one of conventional / ticket-prefix / plain, chosen by majority over the last 15 subjects), and branch= fields so callers branch on typed flags rather than text inference.

Pair with git_commit_apply — context tool gathers state, apply tool validates and commits.

Param	Type	Default
(none)

No approval. Parallel-safe.

git_commit_apply

Composite mutator that validates a one-line subject and runs git commit -F - against the currently staged changes. The following rejections fire before invoking git (deterministic Go, not model judgment):

empty staging (committed=false reason=staged_empty)
empty / whitespace-only message
multi-line message (no body or footer accepted)
subject longer than 72 characters
subject ending in a period

Returns a typed envelope. On success: committed=true sha=<hash> plus post-commit ## unstaged / ## untracked sections. On pre-commit hook failure: committed=false reason=hook_error followed by the hook’s verbatim output. The tool never auto-retries, auto-stages, or amends.

Param	Type	Default
`message`	string	—

Always prompts for approval.

gh_pr_context

Composite read-only snapshot used to open a pull request without parsing multi-step bash output. Returns labeled sections under ## state, ## diff.stat, ## commits.log, and ## pr.template. The ## state block carries deterministic flags callers branch on: resolved_base=, base_resolution= (one of explicit, origin-head, fallback:<name>, unresolved), current_branch=, base_equals_current=, ahead_count=, pushed_to_origin=, and gh_available=.

Base resolution priority: explicit base argument → origin/HEAD symbolic ref → first of main / master / develop that exists locally. The pushed_to_origin check uses git ls-remote --exit-code --heads origin <branch> so empty-remote repos correctly report false without crashing.

Pair with gh_pr_create — context tool gathers state, create tool validates the title and opens the PR.

Param	Type	Default
`base`	string	(auto-resolved from `origin/HEAD` then fallback chain)

No approval.

gh_pr_create

Composite mutator that validates a PR title and opens the pull request through the typed internal/github.Interface adapter. The following rejections fire before dialing the adapter (deterministic Go, not model judgment):

empty title / body / base (created=false reason=validation)
multi-line title
title longer than 72 characters
title ending in a period

Returns a typed envelope. On success: created=true url=<url> number=<n>. On a missing or unauthenticated gh CLI: created=false reason=gh_unavailable so the procedural /git-create-pr can fall through to draft-only output without surfacing an opaque exec failure. On other gh errors: created=false reason=gh_error followed by the gh output verbatim. The tool never auto-retries, auto-edits, or auto-merges.

The adapter behind this tool is internal/github.TypedClient, backed by the go-github/v66 REST client. Auth resolves through a three-tier precedence chain: $GITHUB_TOKEN env var → gh auth token shell-out (one-shot, cached for the session) → ~/.yottacode/github.json (yottacode-native PAT, written by a future yottacode setup github flow). The gh CLI is no longer required for API calls — only optionally used to source the token when $GITHUB_TOKEN isn’t set.

Param	Type	Default
`base`	string	—
`title`	string	—
`body`	string	—
`draft`	bool	`false`

Always prompts for approval.

gh_pr_review_context

Composite read-only fetcher for the procedural /git-review-pr flow. Calls the three Interface read methods (ReadPR, ListPRChecks, ReadPRDiff) and folds their results into one typed snapshot under ## state, ## pr, ## checks.summary, ## checks, and ## diff headers.

The ## state block carries deterministic flags callers branch on: ref=, not_found= (the gh CLI couldn’t resolve the ref to an existing PR), gh_unavailable= (gh missing or unauthenticated), and failing_checks= (comma-separated names of check runs whose conclusion was FAILURE, CANCELLED, TIMED_OUT, or ACTION_REQUIRED). When not_found or gh_unavailable are true the snapshot short-circuits — the pr/checks/diff sections are omitted to keep the model’s branching clean.

Failing-check classification covers both the GraphQL check-run shape (Conclusion populated) and the legacy status-context shape (State=“FAILURE”/“ERROR” with empty Conclusion). The diff is capped at 64 KiB with a truncation marker pointing at gh pr diff <ref> for the full content.

Param	Type	Default
`ref`	string	(uses current branch’s PR)

No approval. Touches the network (not parallel-safe).

gh_pr_update

Composite mutator that rewrites an existing PR’s title and body. Paired with the procedural /git-update-pr slash command for the “follow-up commits made the original description stale” workflow.

Deterministic guarantees:

Title validation (reuses validatePRTitle from gh_pr_create): rejects empty, multi-line, oversize (>72 chars), and trailing-period titles before dialing the adapter.
Non-empty body guard: empty body would clobber the existing PR description, which is almost never intended. Caught in Go with updated=false reason=validation.
Scope-pinned: only edits title and body. Labels, base, reviewers, draft state, milestone, and projects are not accepted — /git-update-pr enforces the same scope at the prompt level.

Returns a typed envelope. On success: updated=true url=<url> number=<n>. On a missing PR: updated=false reason=not_found with a hint pointing at /git-create-pr. On gh-unavailable: updated=false reason=gh_unavailable. On other gh errors: updated=false reason=gh_error with the gh output verbatim. The tool never auto-retries, auto-edits other fields, or auto-merges.

Param	Type	Default
`ref`	string	(uses current branch’s PR)
`title`	string	—
`body`	string	—

Always prompts for approval.

git_push

Composite mutator that pushes the current branch to origin. Deterministic guarantees:

Upstream-aware: detects whether the current branch already tracks an upstream and adds -u origin HEAD only on first push.
Detached-HEAD early exit: rejects the push before invoking git when HEAD isn’t on a branch — returns pushed=false reason=detached_head.
No force-push surface: --force / --force-with-lease are intentionally not accepted. Use the unified git tool when you actually need force-push.

Returns a typed envelope. On success: pushed=true branch=<name> set_upstream=<bool> plus a best-effort PR-URL lookup via internal/github.Interface.ReadPR. When a PR exists for the branch, pr_number=<n> and pr_url=<url> are populated so callers (and /git-push) can surface a “PR updated” footer. When no PR exists, the envelope hints at /git-create-pr as the next step.

Git errors (exit non-zero) populate pushed=false reason=git_error with the verbatim git output. The tool never auto-retries, auto-force-pushes, or rebases to “fix” a rejection.

Param	Type	Default
(none)

Always prompts for approval.

git_log_file

Show history for a single file.

Param	Type	Default
`path`	string	—
`limit`	int	`10`

No approval.

git_blame_lines

Show blame output for a line range in a file.

Param	Type	Default
`path`	string	—
`start`	int	—
`end`	int	—

No approval.

git_merge_base

Find the merge base between two refs.

Param	Type	Default
`base`	string	—
`head`	string	—

No approval.

git_checkpoint

Create a local checkpoint commit from all current changes.

Param	Type	Default
`message`	string	`checkpoint`

Always prompts for approval.

rollback

Reset the git working tree to a target commit. Defaults to HEAD~1. This is destructive and discards uncommitted changes.

Param	Type	Default
`target`	string	`HEAD~1`

Always prompts for approval.

run_tests

Run a test command in the repo. Defaults to go test ./....

Param	Type	Default
`command`	string	`go test ./...`
`path`	string	`.`

No approval.

list_dir

One line per entry: <type>\t<name> where <type> is d (dir), f (file), or l (symlink). Capped at 100 entries.

Param	Type	Default
`path`	string	`.`

No approval.

glob

Doublestar pattern match (** recursive). Returns paths relative to the cwd. Capped at 200 results.

Param	Type	Default	Notes
`pattern`	string	—	e.g. `*/.go`, `internal/agent/*.go`
`cwd`	string	tool’s cwd	Roots the search

No approval.

grep

Prefers rg (ripgrep); falls back to GNU grep -E/-F. Pattern arguments are passed via argv — no shell, no injection.

Param	Type	Default	Notes
`pattern`	string	—	Required
`path`	string	`.`	File or directory
`regex`	bool	`false`	When false, treats pattern as a fixed string
`ignore_case`	bool	`false`
`max_results`	int	`50`	Hard cap

Output is capped at 256 KiB. Exit code 1 (no matches) is treated as “no results”, not as an error.

No approval.

fetch_url

Fetch a single HTTP or HTTPS URL and return capped textual content. This is the local-network fallback for models that do not have provider-native hosted web search.

Param	Type	Default	Notes
`url`	string	—	Required; must start with `http://` or `https://`
`max_bytes`	int	`65536`	Hard cap is `262144`; larger values clamp to the default

The tool only returns textual content types such as HTML, plain text, JSON, XML, and JavaScript responses. Binary content types are rejected.

run_bash

Run a shell command via /bin/sh -c in the session’s cwd.

Param	Type	Default	Notes
`command`	string	—	Passed verbatim to `/bin/sh -c`

Always prompts for approval. Output is exit=<code>\n--- stdout ---\n…\n--- stderr ---\n…, each stream capped at 1 MiB; truncation is announced in the result.

There is no in-process sandbox, and there will not be one — yottacode keeps its core small and does not ship bwrap/firejail/landlock backends. For real isolation, run yottacode inside a container or devcontainer.

git

Unified git tool. Args are passed as a JSON string array, never via the shell, so there’s nothing to escape and nothing to inject.

Param	Type	Default	Notes
`args`	[]string	—	e.g. `["status"]`, `["log", "--oneline", "-n", "5"]`

Approval policy is based on the first arg:

Auto-execute (read-only): status, diff, log, show, blame, grep, ls-files, rev-parse, branch --show-current, etc.
Prompt for approval for everything else (commit, push, pull, branch -D, checkout, reset, rebase, merge, …).

Destructive flags (--force, -f, -D, --hard, --delete, …) are called out in the approval preview with a ⚠ DESTRUCTIVE FLAG(S): prefix so you don’t y past them by reflex.

Stdout is capped at 1 MiB; stderr at 64 KiB.

todo_write

Maintain the agent’s working task plan. The list is owned by the session and rendered as a live card in the TUI’s in-flight area — updates in place on every todo_write call, so the user sees status flips without each call stacking a new card. At turn end one final-state snapshot lands in scrollback as the historical receipt for that turn.

Param	Type	Default	Notes
`todos`	[]object	—	Complete plan; previous list is replaced wholesale

Each item has content (short human-readable description) and status (pending / in_progress / completed, at most one in_progress). No filesystem or network side effects — purely a visibility primitive, so it never prompts for approval.

The model is instructed to call todo_write proactively for any task with three or more distinct steps and to update it as soon as each step finishes. When work has both a design/research phase and an execution phase, the todo list must end at the design-presentation step — implementation todos are only added in a follow-up todo_write call after the user has explicitly agreed to the design, so the plan never pre-stages unapproved work. Pass an empty list to clear the plan; the live card disappears and no end-of-turn snapshot is emitted.

exit_plan_mode

Only callable while /plan mode is active (the registry hides it from the adapter schema otherwise). Takes no arguments — the TUI reads the plan body from the resolved plan file on disk and renders it in the approval card. Matches Claude Code’s ExitPlanMode shape exactly.

Param	Type	Default	Notes
(none)	—	—	The plan content comes from `~/.yottacode/plans/<slug>.md`

If the plan file doesn’t exist or is empty when exit_plan_mode is called, the TUI auto-denies the call with a console notice — the model is expected to write the plan to the file first, then call this tool.

The TUI renders the plan inside an approval card with four hotkeys:

[A] auto-approval — exits plan mode AND turns on auto mode for the implementation, so mutating tools auto-allow without per-call prompts (safety floor still applies: run_bash, git_commit, git_checkpoint, rollback).
[M] manual approval — exits plan mode and the agent resumes execution, but per-tool prompts continue as normal so you can review each step.
[L] later — exits plan mode but ends the turn; the plan stays on disk for resume via /plan list or --plan-resume.
[K] keep planning — stays in plan mode; model receives refinement guidance.

--yolo does NOT skip this approval — that approval is the user-visible signal, not a safety gate.

While /plan is active, every other mutating tool is blocked except writes to the resolved plan file under ~/.yottacode/plans/<slug>.md. Read-only tools auto-allow as usual; writes to the plan file auto-allow too (no per-edit prompt — the plan file is the model’s only legitimate mutation surface during planning). See tui-slash-commands.md#plan-mode for the full plan-mode flow.

Agent

Dispatch a typed subagent. The subagent runs agent.Turn in its own message history, with a filtered tool registry and its own iteration budget. The parent’s adapter context never sees the subagent’s intermediate reasoning or tool calls — only the child’s final reply is returned as the tool result.

Mirrors Claude Code’s Agent / Task tool surface.

Param	Type	Default	Notes
`subagent_type`	string (required)	—	The name of a registered agent definition (e.g. `general-purpose`, `Explore`, `Plan`, or a custom entry under `.yottacode/agents/`).
`prompt`	string (required)	—	The task for the subagent. The subagent has no access to the parent conversation, so be self-contained.
`description`	string	""	A 3-5 word label shown to the user while the subagent runs.
`run_in_background`	boolean	`false`	If true (TUI only), return immediately with a task id; the subagent runs to completion in the background. `oneshot` rejects this with a recoverable error so the model can retry without the flag.

The full documentation — file format for custom agents, the /subagents command, transcript layout, and the recursion + iteration safeguards — is in subagents.md.

Configuring models MCP servers