wip(freestyle/acr): grounding & edit-tool fixes + ACR-compiler experiment

This branch's uncommitted WIP, committed together (entangled at file level).
Distinct pieces of work:

Freestyle QA fixes (this session):
- FileEditTool: pre-validate replace anchor in validateRequest — reject a
  missing/ambiguous target BEFORE the approval gate, mirroring read/write's
  file-not-found / read-before-write pre-checks. Shared not-found/ambiguous
  messages between validate and execute so they can't drift.
- PlanGrounder: add `scanned` flag; when no RepoMapComputedEvent was recorded,
  repoMapPaths is "unknown" not "empty workspace" — skip scope grounding
  (which proves a path ABSENT) so real paths (apps/server/**) aren't falsely
  rejected. Build-manifest check still runs.
- FreestyleDriver: wire scanned=(repoMap!=null); on plan rejection emit a
  session-terminal WorkflowFailedEvent so a rejected run reads FAILED, not the
  COMPLETED-lie (last verdict was the planning-phase WorkflowCompleted).
- ServerModule: resolve project-memory workspace root from the session's bound
  workspace (sessionWorkspaceRoot) instead of boot-static pm.repoRoot(), fixing
  the workspace-binding divergence (correx vs empty scratch dir). Retire tracked
  in Vikunja #266.
- LaunchRegistrationRaceTest: join registered jobs before asserting launchCount
  — computeIfAbsent returns the Job immediately but the fire-and-forget launch
  body lagged awaitAll (the 49-vs-50 flake).

ACR concept-compiler experiment (pre-existing WIP on this branch):
- ExecutionPlanCompiler/Model/PlanLinter, #264 needs-seam (sessionArtifacts),
  LSP diagnostics subsystem (LspDiagnosticEvents/Runner/Lsp4j), BootWorkspace,
  config surface, workflow prompts/schemas, orchestrator advance-don't-rerun.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/workflows/prompts/discovery.md

@@ -22,24 +22,47 @@ Two checks, both grounded in what you actually read:
    endpoint.
 
 Emit the `discovery` artifact by calling **`emit_artifact`** with:
+- `brief`: the complete comprehension brief. Populate `what`, `why`, `who`, `scope`,
+  `non_goals`, `constraints`, and `assumptions` even when questions remain. Use assumptions for
+  reasonable, visible defaults instead of parking on micro-decisions.
 - `ready`: `true` when the request is clear and grounded enough to hand to the analyst; `false`
   when you are raising questions.
 - `questions`: the open questions (empty when `ready` is true). Batch **all** of them into this
   one list — do not ask one at a time. Each entry is an object:
   - `prompt` (required): the question, in full.
-  - `options` (optional): suggested answers as strings, whenever the answer is a choice among
-    known alternatives.
+  - `options` (**required whenever the answer is a choice among known alternatives** — and it
+    almost always is: stack, library, endpoint, layout, priority are all choices among things you
+    can name). Provide 2–4 concrete prefilled answers as strings. An open-ended question with no
+    `options` is only acceptable when no candidate set exists at all. Empty `options` on a
+    choice-question is a defect — enumerate the real candidates you found in the repo.
   - `multiSelect` (optional, default false): true if more than one option may apply.
   - `header` (optional): a 1–2 word label (e.g. "Scope", "Stack", "Endpoint").
 
-**Default to proceeding.** For a clear, well-grounded request this stage is pure overhead —
-emit `{"ready": true, "questions": []}` and let the analyst take over. Only ask when a genuine
+**Default to proceeding.** First inspect enough of the repository to enumerate the whole question
+surface, then ask every genuine operator-only question in one batch. For a clear, well-grounded
+request, proceed with visible assumptions. Do not raise one question, re-enter, and discover
+another question that the same initial inspection could have exposed.
+
+**Converge once answered.** If the decision history above already contains the operator's answers
+to your questions, you are done vetting — emit the brief with `ready: true` and empty `questions`.
+Do NOT re-explore the repo hunting for new questions after the operator has answered; fold their
+answers into the brief and hand off. You get **one** clarification round: ask everything up front,
+then commit. Endless re-inspection is a failure, not diligence.
 fork or contradiction blocks planning. Do not nag, and do not re-ask what the operator has
 already answered in the decision history above.
 
 Example (needs input):
 ```json
 {
+  "brief": {
+    "what": "Build a browser client for the existing session API.",
+    "why": "Operators need a visual session surface.",
+    "who": ["operators"],
+    "scope": ["browser session client"],
+    "non_goals": ["server protocol redesign"],
+    "constraints": ["reuse the existing endpoint"],
+    "assumptions": []
+  },
   "ready": false,
   "questions": [
     {"prompt": "Which frontend stack should the UI target?",
@@ -52,5 +75,17 @@ Example (needs input):
 
 Example (clear — the common case):
 ```json
-{ "ready": true, "questions": [] }
+{
+  "brief": {
+    "what": "Add the requested deterministic validation gate.",
+    "why": "Prevent invalid output from reaching review.",
+    "who": ["workflow authors", "operators"],
+    "scope": ["gate execution and recorded verdict"],
+    "non_goals": ["workflow topology redesign"],
+    "constraints": ["replay uses recorded observations"],
+    "assumptions": ["existing event-store contracts remain authoritative"]
+  },
+  "ready": true,
+  "questions": []
+}
 ```