fix(engine): resolve @-links per scope, and settle the remaining ADK gaps

[Cidan]

Closes the last items from the ADK audit. One real bug, two pieces of dead code that should not be wired, one deferred with a reason, and one item that was my error.

@-links resolve per scope (real bug)

An @-link in ~/.claude/CLAUDE.md was resolved against the project root. Your actual case: it contains @RTK.md, which sits right next to it, and ask looked for <repo>/RTK.md and silently found nothing. It became reachable when #133 started loading the user-global scope.

type ContextScope struct {
	Dir  string   // where instruction files are searched
	Root string   // what this scope's @-links resolve against
}

LoadedContextDoc.Root and Rule.Root carry it, BuildSystemPrompt groups links by root before resolving, and the JIT rule path uses r.Root. Verified against your real ~/.claude:

included_docs block present: true
   <file path="/home/antonio/.claude/CLAUDE.md">
   <file path="/home/antonio/.claude/RTK.md">
RTK.md content reached the prompt: true

functioncallmodifier removed, not enabled

It injects synthetic arguments into tool declarations at request time. ask needed that for the required description phrase — which is now a static field on every native tool's params struct, so there is nothing left to inject. It had been registered with Predicate: func(string) bool { return false } since #132.

Bridge tools still get description added to their input schema in pkg/tools/bridge.go, because their input types come from the MCP handler cores. That's a one-time build at construction, not per-request surgery.

agenttool rejected, four dead builders deleted

agent_tool.go:142 builds its own runner with a hardcoded config:

runner.New(runner.Config{
	AppName:         t.agent.Name(),
	Agent:           t.agent,
	SessionService:  sessionService,
	ArtifactService: artifact.InMemoryService(),
	MemoryService:   memory.InMemoryService(),
})

No PluginConfig, so a subagent would lose retryandreflect. MemoryService is in-memory, so it would lose ask's memory. And it produces one tool per agent, replacing task(agent: "foo") with a tool named foo.

The task tool's nested engine.Run goes through RunnerBuilder — ask's plugins, memory service, and file session service — and keeps the background-job path and the subagent UI events. BuildResearchSubagent / BuildNamedSubagent / BuildResearchAgentTool / BuildNamedAgentTool had no production callers and are deleted.

toolconfirmation deferred

It emits adk_request_confirmation, pauses the run, and resumes on a function response. ask has no suspend/resume path for a chat turn, so adopting it means building one — a design change, not a bug fix. Approval stays ToolEnv.ApprovalDenied, which blocks on the modal and returns the denial inline.

IsConfirmationCall / UnwrapConfirmationCall stay wired in the event loops, because an MCP server can declare confirmation on its own tools and those branches render the inner intent correctly if it ever fires. FormatConfirmationResponse had no callers at all and is deleted.

Correction: the deferred registry was not a bug

I listed "empty deferred registry on the engine path" as a gap. That was wrong. The task tool already threads the parent session's registry:

deferredFn := func() []tools.Tool { … sess.deferredTools() … }
toolsList = tools.CoreTools(subEnv, deferredFn, true)
engine.Run(runCtx, engine.RunOptions{ Tools: toolsList })

engine.Run uses opts.Tools when non-empty, so GetDefaultToolFactory() and its nil registry are never reached. Subagents do see MCP and linear_*. The nil applies only to a pure headless engine.Run with no tools passed, where there genuinely is no registry source — MCP isn't connected and the linear tools live in cmd/ask.

Docs

docs/adk-20-upgrade.md gains a Deliberate departures section, so none of these gets wired later by someone reading an import as an intention.

Tests

• global-scope @-links resolve under ~/.claude, and do not pick up a same-named file in the project
• project-scope links still resolve under the project root
• every coding tool declares description statically — the reason functioncallmodifier is unnecessary
• DefaultPlugins stays free of the modifier

make test green across all 9 packages.

🤖 Generated with Claude Code