diff --git a/architect/architect-run.sh b/architect/architect-run.sh
index b3d2513..16be18b 100755
--- a/architect/architect-run.sh
+++ b/architect/architect-run.sh
@@ -98,7 +98,7 @@ PROMPT=$(build_architect_prompt)
 formula_worktree_setup "$WORKTREE"
 
 # ── Run agent ─────────────────────────────────────────────────────────────
-export CLAUDE_MODEL="sonnet"
+export CLAUDE_MODEL="opus"
 
 agent_run --worktree "$WORKTREE" "$PROMPT"
 log "agent_run complete"
diff --git a/formulas/run-architect.toml b/formulas/run-architect.toml
index 4d923f3..5a2df6a 100644
--- a/formulas/run-architect.toml
+++ b/formulas/run-architect.toml
@@ -1,13 +1,12 @@
-# formulas/run-architect.toml — Architect formula
+# formulas/run-architect.toml — Architect formula (stub)
 #
 # Executed by architect-run.sh via cron — strategic decomposition of vision
 # issues into development sprints.
 #
-# This formula orchestrates the architect agent's workflow:
-#   Step 1: Preflight — validate prerequisites and identify target issue
-#   Step 2: Research + pitch — analyze codebase and write sprint pitch
-#   Step 3: Sprint PR creation with questions (issue #101)
-#   Step 4: Answer parsing + sub-issue filing (issue #102)
+# This is a stub formula — steps will be filled in by follow-up issues:
+#   #100: research + design fork identification
+#   #101: sprint PR creation with questions
+#   #102: answer parsing + sub-issue filing
 #
 # AGENTS.md maintenance is handled by the gardener (#246).
 
@@ -22,113 +21,16 @@ files = ["VISION.md", "AGENTS.md"]
 # Sprints directory tracked in ops repo
 
 [[steps]]
-id    = "preflight"
-title = "Preflight: validate prerequisites and identify target vision issue"
+id    = "placeholder"
+title = "TODO: implement formula steps"
 description = """
-This step performs preflight checks and identifies the most unblocking vision issue.
+This step is a placeholder. The actual formula steps will be implemented in
+follow-up issues:
 
-Actions:
-1. Pull latest code from both disinto repo and ops repo
-2. Read prerequisite tree from $OPS_REPO_ROOT/prerequisites.md
-3. Fetch open issues labeled 'vision' from Forgejo API
-4. Check for open architect PRs on ops repo (handled by #101/#102)
-5. If open architect PRs exist or no vision issues, signal PHASE:done
+- #100: research + design fork identification
+- #101: sprint PR creation with questions
+- #102: answer parsing + sub-issue filing
 
-Skip conditions:
-- If open architect PRs exist on ops repo, signal PHASE:done
-- If no vision issues are found, signal PHASE:done
-
-Output:
-- Sets ARCHITECT_TARGET_ISSUE to the issue number of the selected vision issue
-- Exports VISION_ISSUES as a JSON array of issue objects
-"""
-
-[[steps]]
-id    = "research_pitch"
-title = "Research + pitch: analyze codebase and write sprint pitch"
-description = """
-This step performs deep codebase research and writes a sprint pitch for the
-selected vision issue.
-
-Actions:
-
-1. Read the codebase deeply:
-   - Read all files mentioned in the issue body
-   - Search for existing interfaces that could be reused
-   - Check what infrastructure already exists
-
-2. Assess complexity and cost:
-   - How many files/subsystems are touched?
-   - What new infrastructure would need to be maintained after this sprint?
-   - What are the risks (breaking changes, security implications, integration complexity)?
-   - Is this mostly gluecode or greenfield?
-
-3. Write sprint pitch to scratch file for PR creation step (#101):
-
-# Sprint pitch: <name>
-
-## Vision issues
-- #N — <title>
-
-## What this enables
-<what the project can do after this sprint that it can't do now>
-
-## What exists today
-<current state — infrastructure, interfaces, code that can be reused>
-
-## Complexity
-<number of files, subsystems, estimated sub-issues>
-<gluecode vs greenfield ratio>
-
-## Risks
-<what could go wrong, what breaks if this is done badly>
-
-## Cost — new infra to maintain
-<what ongoing maintenance burden does this sprint add>
-<new services, cron jobs, formulas, agent roles>
-
-## Recommendation
-<architect's assessment: worth it / defer / alternative approach>
-
-IMPORTANT: Do NOT include design forks or questions yet. The pitch is a go/no-go
-decision for the human. Questions come only after acceptance.
-
-Output:
-- Writes sprint pitch to $SCRATCH_FILE (/tmp/architect-{project}-scratch.md)
-- The pitch serves as input for sprint PR creation step (#101)
-"""
-
-[[steps]]
-id    = "sprint_pr_creation"
-title = "Sprint PR creation with questions (issue #101)"
-description = """
-This step creates a PR on the ops repo with the sprint proposal and design questions.
-
-Actions:
-1. Read the sprint pitch from the scratch file
-2. Create a PR on the ops repo with the sprint proposal
-3. Include design questions and forks for human review
-4. Tag the original vision issue in the PR description
-
-Output:
-- Creates PR on ops repo with sprint proposal
-- Links to original vision issue(s)
-- Includes design questions for architect-human conversation
-"""
-
-[[steps]]
-id    = "answer_parsing"
-title = "Answer parsing + sub-issue filing (issue #102)"
-description = """
-This step processes human answers to design questions and files sub-issues.
-
-Actions:
-1. Monitor PR comments for human responses to design questions
-2. Parse answers and extract design decisions
-3. File concrete sub-issues for each accepted design fork path
-4. Close or update the sprint PR based on decisions
-
-Output:
-- Sub-issues filed in disinto repo with proper dependencies
-- Sprint PR updated or closed based on design decisions
+The architect formula will decompose vision items into coherent sprints,
+identify design forks, and file sub-issues after design decisions are made.
 """