@@ -19,6 +19,8 @@ This is about **operative** instructions — a skill's own steps telling the age
 
 The Skill tool takes one skill per call. A step that needs two skills is two calls, not one call with two names — say so (`Call the Skill tool twice, for "grilling" and "domain-modeling"`), not "call it with X and Y," which reads as a single call taking both.
 
+This whole convention only holds when the named skill is **model-invoked**. A user-invoked skill can never be reached this way, full stop — per the invariant above, no other skill can call it, including by naming it to the Skill tool. When a step's precondition is a user-invoked skill (e.g. `setup-matt-pocock-skills`), phrase it as an instruction for the human to act on — "tell the user to run `/setup-matt-pocock-skills`" — never as a Skill tool call.
+
 ## Passive vs active domain work
 
 Merely _reading_ `CONTEXT.md` for vocabulary is a one-line prose pointer, not the `domain-modeling` skill. Only the active build/sharpen discipline (challenge terms, edge-case scenarios, write ADRs, update `CONTEXT.md` inline) is `domain-modeling`.
@@ -0,0 +1,11 @@
+---
+"mattpocock-skills": patch
+---
+
+Stop skills from trying to reach user-invoked skills through the Skill tool — fix cross-skill references that violated the "no other skill can call it" invariant in `.agents/invocation.md`, in `to-spec`, `wayfinder`, `to-tickets`, `triage`, `code-review`, and `diagnosing-bugs`.
+
+- `to-spec`, `wayfinder`, `to-tickets`, `triage`, and `code-review` each carried a precondition ("...run `/setup-matt-pocock-skills` if not") that PR #878 rewrote into a literal `Call the Skill tool with "setup-matt-pocock-skills"` instruction. `setup-matt-pocock-skills` is user-invoked, so none of these skills — user-invoked or model-invoked — can call it. Reworded all five as instructions for the agent to tell the human to run it instead.
+- `diagnosing-bugs`'s Phase 6 post-mortem hand off to `improve-codebase-architecture` (also user-invoked) the same way, from an autonomous, often-unattended bug-fixing flow with no human in the loop to catch the failed call. Removed the hand-off outright rather than softening it — it rarely fired in practice. Phase 6 is now "Cleanup" only; the mechanical checklist is untouched.
+- Added a carve-out paragraph to `.agents/invocation.md`'s "Dependencies between them" section: the `Call the Skill tool with "name"` convention only applies when the named skill is model-invoked. This is the section PR #878 introduced without reconciling it against the user-invoked/model-invoked invariant stated eight lines above it — the gap is most of why this bug reached six call sites instead of one.
+
+Fixes #453.
@@ -10,7 +10,7 @@ Two-axis review of the diff between `HEAD` and a fixed point the user supplies:
 
 Both axes run as **parallel sub-agents** so they don't pollute each other's context, then this skill aggregates their findings.
 
-The issue tracker should have been provided to you — call the Skill tool with "setup-matt-pocock-skills" if `docs/agents/issue-tracker.md` is missing.
+The issue tracker should have been provided to you. If `docs/agents/issue-tracker.md` is missing, tell the user to run `/setup-matt-pocock-skills`.
 
 ## Process
 
 
@@ -127,7 +127,7 @@ If a correct seam exists:
 4. Watch it pass.
 5. Re-run the Phase 1 feedback loop against the original (un-minimised) scenario.
 
-## Phase 6 — Cleanup + post-mortem
+## Phase 6 — Cleanup
 
 Required before declaring done:
 
@@ -136,5 +136,3 @@ Required before declaring done:
 - [ ] All `[DEBUG-...]` instrumentation removed (`grep` the prefix)
 - [ ] Throwaway prototypes deleted (or moved to a clearly-marked debug location)
 - [ ] The hypothesis that turned out correct is stated in the commit / PR message — so the next debugger learns
-
-**Then ask: what would have prevented this bug?** If the answer involves architectural change (no good test seam, tangled callers, hidden coupling) hand off by calling the Skill tool with "improve-codebase-architecture" and the specifics. Make the recommendation **after** the fix is in, not before — you have more information now than when you started.
@@ -6,7 +6,7 @@ disable-model-invocation: true
 
 This skill takes the current conversation context and codebase understanding and produces a spec. Do NOT interview the user — just synthesize what you already know.
 
-The issue tracker and triage label vocabulary should have been provided to you — call the Skill tool with "setup-matt-pocock-skills" if not.
+The issue tracker and triage label vocabulary should have been provided to you. If not, tell the user to run `/setup-matt-pocock-skills`.
 
 ## Process
 
 
@@ -8,7 +8,7 @@ disable-model-invocation: true
 
 Break a plan, spec, or conversation into a set of **tickets** — tracer-bullet vertical slices, each declaring the tickets that **block** it.
 
-The issue tracker and triage label vocabulary should have been provided to you — call the Skill tool with "setup-matt-pocock-skills" if not.
+The issue tracker and triage label vocabulary should have been provided to you. If not, tell the user to run `/setup-matt-pocock-skills`.
 
 ## Process
 
 
@@ -40,7 +40,7 @@ For a PR, the same states read against the attached code: `ready-for-agent` mean
 
 Every triaged issue should carry exactly one category role and one state role. If state roles conflict, flag it and ask the maintainer before doing anything else.
 
-These are canonical role names — the actual label strings used in the issue tracker may differ. The mapping should have been provided to you - call the Skill tool with "setup-matt-pocock-skills" if not.
+These are canonical role names — the actual label strings used in the issue tracker may differ. The mapping should have been provided to you. If not, tell the user to run `/setup-matt-pocock-skills`.
 
 State transitions: an unlabeled issue normally goes to `needs-triage` first; from there it moves to `needs-info`, `ready-for-agent`, `ready-for-human`, or `wontfix`. `needs-info` returns to `needs-triage` once the reporter replies. The maintainer can override at any time — flag transitions that look unusual and ask before proceeding.
 
 
@@ -22,7 +22,7 @@ The map is a single issue on this repo's issue tracker, labelled `wayfinder:map`
 
 The map is an **index**, not a store. It lists the decisions made and points at the tickets that hold their detail; a decision lives in exactly one place — its ticket — so the map never restates it, only gists it and links.
 
-**Where the map, its child tickets, blocking, and frontier queries physically live is tracker-specific.** The issue tracker should have been provided to you — call the Skill tool with "setup-matt-pocock-skills" if not. Consult the tracker doc's "Wayfinding operations" section for how _this_ repo expresses them. If no tracker has been provided, default to the local-markdown tracker.
+**Where the map, its child tickets, blocking, and frontier queries physically live is tracker-specific.** The issue tracker should have been provided to you. If not, tell the user to run `/setup-matt-pocock-skills`. Consult the tracker doc's "Wayfinding operations" section for how _this_ repo expresses them. If no tracker has been provided, default to the local-markdown tracker.
 
 ### The map body