fix(skills): document a session_log call the tool would actually accept

Nine skills documented the payload. None named `session_id`, which is the
tool's only required field. So every documented call was one the tool rejects —
an agent following any of them either failed the call or invented an id, and
invented ids do not group, which means the pass-rate the /pass-rate endpoint
computes was being assembled from entries that cannot be joined.

Found by the #19 pressure test against `debug`, which invented
`debug-signed-artifact-missing-2026-08-29` and said so: "my three entries are
only groupable by luck of naming". The grep afterwards showed it was fleet-wide,
not a `debug` bug.

Also removed: `duration_ms: <wall-clock>` in eight of them. An agent does not
observe a clock. The same run omitted it "rather than fabricate", which is the
good outcome; the bad outcome is the run that fabricates, and a made-up number
in a metrics stream is worse than a missing one. It is an optional field and is
now simply absent.

bin/check-session-log gates both, with tests. This is exactly the case #19 has
in mind for a small tool over prose: the rule is a grep, so it should be a gate,
not a note asking people to remember.

Closes part of #36
Bump-Type: patch

.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "skills",
   "description": "Mathias's engineering skills library, plus the hooks and MCP servers that make it enforceable: TDD, clean code, debugging, specs, discovery, CI, and secret hygiene.",
-  "version": "0.13.0",
+  "version": "0.13.2",
   "author": {
     "name": "Mathias",
     "url": "https://git.d-ma.be/mathias"

.mcp.json

@@ -14,7 +14,7 @@
     }
   },
   "_parked": {
-    "_reason": "cad and gitea-mcp are proxied and reachable (tailscale serve 8445 -> 127.0.0.1:31877, 8446 -> 127.0.0.1:30340; both answer 401 unauthenticated, so auth is enforced and the path is right). They stay parked because their static tokens live in the 1Password AgentSecrets vault, and this host's op identity sees only HomeLab -- 'op vault list' returns HomeLab alone, and resolving op://HomeLab/gitea-mcp-shared-token/password or op://HomeLab/CAD_STATIC_TOKEN/password fails with 'could not find item'. That is infra#224 (AgentSecrets not visible to koala's service account), NOT the OAuth-discovery bug both issues warned about. Enabling is: make the vault visible, add the two op:// references to ~/.op-env, move these entries into mcpServers. See mathias/skills#32 and #33.",
+    "_reason": "cad and gitea-mcp are proxied, reachable and AUTHENTICATING: tailscale serve 8445 -> 127.0.0.1:31877 and 8446 -> 127.0.0.1:30340; an MCP initialize with the correct bearer returns 200 from both (serverInfo gitea-mcp 0.1.0, cad aed2aaf). They stay parked only because nothing puts those two tokens into the session environment. Both live in the 1Password AgentSecrets vault, and by deliberate design (infra#224, closed) no single identity on koala reads both vaults: koala-homelab is HomeLab-only and resolves ~/.op-env, koala-agentsecrets-write is AgentSecrets-only and lives in ~/.op-agent-write.env. Adding an AgentSecrets reference to ~/.op-env does NOT degrade gracefully -- `op run` fails wholesale and every other token, BRAIN_MCP_TOKEN included, goes unresolved with it. Enabling needs a read-scoped AgentSecrets identity in the session-env path; see mathias/skills#32, #33.",
     "cad": {
       "type": "http",
       "url": "https://koala.tail30472e.ts.net:8445/mcp",

Taskfile.yml

@@ -110,7 +110,11 @@ tasks:
         #    harness instead of erroring.
         sh '{{.TASKFILE_DIR}}/bin/check-surfaces' '{{.TASKFILE_DIR}}' || fail=1
 
-        # 5. Plugin manifest version must match the latest tag, or installers
+        # 5. A documented session_log call must be one the tool would accept:
+        #    session_id is its only required field, and nine skills omitted it.
+        sh '{{.TASKFILE_DIR}}/bin/check-session-log' '{{.TASKFILE_DIR}}' || fail=1
+
+        # 6. Plugin manifest version must match the latest tag, or installers
         #    never see the update (Claude Code gates updates on this field).
         if [ -f '{{.PLUGIN_MANIFEST}}' ]; then
           manifest_v=$(sed -n 's/.*"version"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' '{{.PLUGIN_MANIFEST}}' | head -1)

bin/check-session-log

@@ -0,0 +1,39 @@
+#!/bin/sh
+# check-session-log — a skill that documents a session_log call must document a
+# call the tool would actually accept.
+#
+# Nine skills documented the payload and none named `session_id`, which is the
+# tool's only REQUIRED field. An agent following any of them either failed the
+# call or invented an id — and invented ids do not group, so the pass-rate the
+# endpoint computes was being assembled from entries that could not be joined
+# (#36, found by a pressure test against `debug`).
+#
+# Also rejected: `duration_ms: <wall-clock>`. An agent does not observe a clock.
+# A documented field nobody can honestly populate gets fabricated or silently
+# dropped, and fabricated numbers in a metrics stream are worse than no numbers.
+#
+# Usage: check-session-log [checkout-root]
+
+set -u
+
+ROOT=${1:-$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)}
+fail=0
+
+for dir in "$ROOT"/skills/*/; do
+  [ -f "$dir/SKILL.md" ] || continue
+  name=$(basename "$dir")
+
+  grep -q 'session_log' "$dir/SKILL.md" || continue
+
+  if ! grep -q 'session_id' "$dir/SKILL.md"; then
+    echo "ERROR: skills/$name documents session_log without session_id — the tool's only required field" >&2
+    fail=1
+  fi
+
+  if grep -q 'duration_ms:[[:space:]]*<' "$dir/SKILL.md"; then
+    echo "ERROR: skills/$name documents duration_ms as a placeholder an agent cannot measure — omit it or pass a real measurement" >&2
+    fail=1
+  fi
+done
+
+exit $fail

skills/cad-babysit/SKILL.md

@@ -234,8 +234,8 @@ wrong" — it means "nothing on the known list is wrong."
 Call `session_log` once at the end of every phase to record the outcome.
 
 **At end of each phase:**
-- `session_log` with `{skill: "cad-babysit", phase: "<phase-name>", final_status: "pass" |
+- `session_log` with `{session_id: "<this session's id>", skill: "cad-babysit", phase: "<phase-name>", final_status: "pass" |
-  "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root:
+  "fail" | "skip", message: "<one-line summary>", project_root:
   "<absolute path>"}`
 
 **Phases for this skill:** query, read-comments, read-actions-logs, classify-fault-vs-outcome,

skills/code-review/SKILL.md

@@ -253,7 +253,7 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of each phase:**
-- `session_log` with `{skill: "code-review", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "code-review", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Phases for this skill:** phase-0-iron-laws, phase-1-context, phase-2-architectural-analysis, phase-3-go-checklist, phase-4-code-smell-detection, phase-5-test-quality
 

skills/debug/SKILL.md

@@ -154,7 +154,7 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of each phase:**
-- `session_log` with `{skill: "debug", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "debug", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Phases for this skill:** read-failure, generate-hypotheses, output
 

skills/experiment-spec/SKILL.md

@@ -185,7 +185,7 @@ If silhouette ≤ 0.20:
 
 **After experiment concludes:**
 - `brain_write` to `jepa-fx/failures/` with any new failure modes discovered
-- `session_log` with outcome
+- `session_log` with `{session_id: "<this session's id>", skill: "experiment-spec", phase: "conclude", final_status: "pass" | "fail" | "skip", message: "<one-line outcome>"}`
 
 ## Cross-References
 

skills/feature-spec/SKILL.md

@@ -245,7 +245,7 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of each phase:**
-- `session_log` with `{skill: "feature-spec", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "feature-spec", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Phases for this skill:** draft
 

skills/session-retrospective/SKILL.md

@@ -116,7 +116,7 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of each phase:**
-- `session_log` with `{skill: "session-retrospective", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "session-retrospective", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Phases for this skill:** surfaced
 

skills/spec-driven-dev/SKILL.md

@@ -332,7 +332,7 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of each phase:**
-- `session_log` with `{skill: "spec-driven-dev", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "spec-driven-dev", phase: "<phase-name>", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Phases for this skill:** specify, plan, tasks, implement
 

skills/tdd/SKILL.md

@@ -406,13 +406,13 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of `red` phase:**
-- `session_log` with `{skill: "tdd", phase: "red", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "tdd", phase: "red", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **At end of `green` phase:**
-- `session_log` with `{skill: "tdd", phase: "green", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "tdd", phase: "green", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **At end of `refactor` phase:**
-- `session_log` with `{skill: "tdd", phase: "refactor", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "tdd", phase: "refactor", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Status semantics:**
 - `pass` — the phase's intended outcome was reached (red: test fails as expected; green: test passes; refactor: tests still pass after refactor).

skills/trainer/SKILL.md

@@ -231,10 +231,10 @@ Pass-rate is computed downstream by the `/pass-rate` HTTP endpoint, which
 treats `pass` as success, `fail` as failure, `skip` as neither.
 
 **At end of `read` phase:**
-- `session_log` with `{skill: "trainer", phase: "read", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "trainer", phase: "read", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **At end of `write` phase:**
-- `session_log` with `{skill: "trainer", phase: "write", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", duration_ms: <wall-clock>, project_root: "<absolute path>"}`
+- `session_log` with `{session_id: "<this session's id>", skill: "trainer", phase: "write", final_status: "pass" | "fail" | "skip", message: "<one-line summary>", project_root: "<absolute path>"}`
 
 **Phases for this skill:** read, write
 

tests/check_session_log_test.sh

@@ -0,0 +1,67 @@
+#!/bin/sh
+# Tests for bin/check-session-log.
+#
+# The regression: nine skills documented a session_log payload and not one of
+# them named `session_id` — the tool's ONLY required field. Every documented
+# call was incomplete, so an agent following any of them either failed the call
+# or invented an id, and invented ids do not group. Found by a pressure test
+# against `debug`, then found to be fleet-wide (#36).
+#
+# Also gated: `duration_ms: <wall-clock>`, which an agent cannot measure. A
+# documented field nobody can honestly populate gets fabricated or silently
+# dropped; both are worse than omitting it.
+
+set -u
+
+ROOT=$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)
+SUT="$ROOT/bin/check-session-log"
+
+pass=0
+fail=0
+WORK=${TMPDIR:-/tmp}/check_session_log_test.$$
+
+if [ ! -f "$SUT" ]; then
+  printf 'FAIL: %s does not exist\n' "$SUT"
+  exit 1
+fi
+
+cleanup() { rm -rf "$WORK"; }
+trap cleanup EXIT INT TERM
+
+# fixture <name> <body> — a checkout with one skill whose SKILL.md is <body>.
+fixture() {
+  _f="$WORK/$1"
+  mkdir -p "$_f/skills/alpha"
+  printf -- '---\nname: alpha\ndescription: a\n---\n\n%s\n' "$2" > "$_f/skills/alpha/SKILL.md"
+  printf '%s' "$_f"
+}
+
+# expect <rc> <label> <fixture> [needle]
+expect() {
+  _want=$1; _label=$2; _fx=$3; _needle=${4:-}
+  _out=$(sh "$SUT" "$_fx" 2>&1); _rc=$?
+  if [ "$_rc" -ne "$_want" ]; then
+    fail=$((fail + 1)); printf '  FAIL %s (want rc=%s got %s)\n%s\n' "$_label" "$_want" "$_rc" "$_out"; return
+  fi
+  if [ -n "$_needle" ] && ! printf '%s' "$_out" | grep -q "$_needle"; then
+    fail=$((fail + 1)); printf '  FAIL %s (rc ok, report never says %s)\n%s\n' "$_label" "$_needle" "$_out"; return
+  fi
+  pass=$((pass + 1)); printf '  ok   %s\n' "$_label"
+}
+
+expect 0 'a skill that never mentions session_log is fine' \
+  "$(fixture quiet 'Just a skill. No logging here.')"
+
+expect 0 'a documented call naming session_id passes' \
+  "$(fixture good 'Call `session_log` with `{session_id: "<id>", skill: "alpha", phase: "red", final_status: "pass"}`')"
+
+expect 1 'a documented call omitting session_id fails' \
+  "$(fixture bad 'Call `session_log` with `{skill: "alpha", phase: "red", final_status: "pass"}`')" \
+  'session_id'
+
+expect 1 'documenting duration_ms as wall-clock fails' \
+  "$(fixture clock 'Call `session_log` with `{session_id: "<id>", skill: "alpha", duration_ms: <wall-clock>}`')" \
+  'duration_ms'
+
+printf '\ncheck_session_log: %d passed, %d failed\n' "$pass" "$fail"
+[ "$fail" -eq 0 ]