Added CODE_CONVENTIONS.md and linters to enforce it, and applied it across the codebase

CODE_CONVENTIONS.md sets out the conventions for Go code in this
repository: naming, layout, comments, errors, logging, configuration and
tests. .golangci.json enables the linters that check the parts that can be
checked (each limited to the rules the conventions use); the rest is
applied by hand.

Applied across the codebase:
- Naming: full-word names in application code, initialisms in one case
  (BuyerID, PrintJSON, PrintYAML, ocdsGetBuyerID), no names shadowing
  built-ins (min/max are minGap/maxGap), mustRaw renamed rawJSON as it
  returns nil rather than panicking, and config.ConfigLevelToLogLevel
  renamed LevelToLogLevel.
- Layout: lines kept to 80 characters where possible, assignments taken
  out of if and for statements that don't fit, wrapped arguments all on
  one line or one per line, steps separated by blank lines, no else after
  a return, function and struct literals wrapped.
- Comments: doc comments on every exported name (including each section's
  Map, Flatten, TypeOf, ValueOf and SetValue), section banners, British
  spelling.
- Errors: a created error starts with its package name, a wrapping error
  adds only what was being done, sentinels in one commented var block,
  errors.Is and errors.As in place of == and type assertions, and no
  err := shadowing of a named result. That fixes the mock server losing
  its access log's close error.
- Logging: the fetcher passes its workers an untagged logger, so
  findatender's lines are tagged with their own component rather than
  with fetcher's as well; cmd/mock-fts logs "stopped" with slog.
- Configuration: util.WithTimeout (moved from the websocket package)
  applies a timeout of 0 or less as no limit, used for the websocket
  write and ping, TCP close and tcpserver shutdown timeouts; every setting
  documents what 0 or empty means, including the rate limit rule's keys
  in internal/config/README.md.
- Tests: related tests merged into table-driven ones with named cases.

Separately from CODE_CONVENTIONS.md, internal/store/README.md gains a soft
SQL style convention for the queries in internal/store/queries.go, and the
queries are reformatted to follow it.

internal/findatender/api_test.go

@@ -34,7 +34,7 @@ func testConfig(level string) *config.JobSearchConfig {
 func quietLogs(t *testing.T, h slog.Handler) {
 	t.Helper()
 	if h == nil {
-		h = slog.NewTextHandler(io.Discard, nil)
+		h = slog.DiscardHandler
 	}
 	prev := slog.Default()
 	slog.SetDefault(slog.New(h))
@@ -44,13 +44,18 @@ func quietLogs(t *testing.T, h slog.Handler) {
 }
 
 // newTestFT starts h on a test server and returns a FindATender pointed at it.
-func newTestFT(t *testing.T, level string, h http.HandlerFunc) (*FindATender, *httptest.Server) {
+func newTestFT(
+	t *testing.T, level string, h http.HandlerFunc,
+) (*FindATender, *httptest.Server) {
 	t.Helper()
 	quietLogs(t, nil)
+
 	srv := httptest.NewServer(h)
 	t.Cleanup(srv.Close)
+
 	ft := New(testConfig(level), srv.URL)
 	t.Cleanup(ft.Shutdown)
+
 	return ft, srv
 }
 
@@ -161,22 +166,40 @@ func TestFetchURIRateLimit(t *testing.T) {
 	}{
 		{"not allowed", "0", false, ErrRateLimitExceeded, "", 1},
 		{"allowed, retries", "0", true, nil, "", 2},
-		{"allowed, bad retry-after", "soon", true, nil, "unknown retry-after value", 1},
-		{"allowed, missing retry-after", "", true, nil, "unknown retry-after value", 1},
+		{
+			"allowed, bad retry-after",
+			"soon",
+			true,
+			nil,
+			"unknown retry-after value",
+			1,
+		},
+		{
+			"allowed, missing retry-after",
+			"",
+			true,
+			nil,
+			"unknown retry-after value",
+			1,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			var hits atomic.Int32
-			ft, srv := newTestFT(t, "warn", func(w http.ResponseWriter, r *http.Request) {
-				if hits.Add(1) == 1 {
-					if tt.retryAfter != "" {
-						w.Header().Set("Retry-After", tt.retryAfter)
+			ft, srv := newTestFT(
+				t,
+				"warn",
+				func(w http.ResponseWriter, r *http.Request) {
+					if hits.Add(1) == 1 {
+						if tt.retryAfter != "" {
+							w.Header().Set("Retry-After", tt.retryAfter)
+						}
+						w.WriteHeader(http.StatusTooManyRequests)
+						return
 					}
-					w.WriteHeader(http.StatusTooManyRequests)
-					return
-				}
-				io.WriteString(w, packageJSON("", releaseJSON("ocds-1", "1")))
-			})
+					io.WriteString(w, packageJSON("", releaseJSON("ocds-1", "1")))
+				},
+			)
 
 			res, err := ft.fetchURI(srv.URL+"/x", tt.allowRateLimit)
 			switch {
@@ -217,7 +240,8 @@ func TestFetchURIRateLimitCancelled(t *testing.T) {
 	}()
 
 	start := time.Now()
-	if _, err := withCtx.fetchURI(srv.URL, true); !errors.Is(err, ErrFetchCancelled) {
+	_, err := withCtx.fetchURI(srv.URL, true)
+	if !errors.Is(err, ErrFetchCancelled) {
 		t.Fatalf("err = %v, want ErrFetchCancelled", err)
 	}
 	if time.Since(start) > 5*time.Second {
@@ -233,7 +257,8 @@ func TestFetchURIRateLimitTwice(t *testing.T) {
 		w.Header().Set("Retry-After", "0")
 		w.WriteHeader(http.StatusTooManyRequests)
 	})
-	if _, err := ft.fetchURI(srv.URL, true); !errors.Is(err, ErrRateLimitExceeded) {
+	_, err := ft.fetchURI(srv.URL, true)
+	if !errors.Is(err, ErrRateLimitExceeded) {
 		t.Fatalf("err = %v, want ErrRateLimitExceeded", err)
 	}
 	if n := hits.Load(); n != 2 {
@@ -247,10 +272,14 @@ func TestFetchURIUnexpectedStatus(t *testing.T) {
 		http.StatusNotFound, http.StatusInternalServerError,
 	} {
 		t.Run(http.StatusText(status), func(t *testing.T) {
-			ft, srv := newTestFT(t, "warn", func(w http.ResponseWriter, r *http.Request) {
-				w.WriteHeader(status)
-				io.WriteString(w, packageJSON("", releaseJSON("ocds-1", "1")))
-			})
+			ft, srv := newTestFT(
+				t,
+				"warn",
+				func(w http.ResponseWriter, r *http.Request) {
+					w.WriteHeader(status)
+					io.WriteString(w, packageJSON("", releaseJSON("ocds-1", "1")))
+				},
+			)
 			_, err := ft.fetchURI(srv.URL, true)
 			if !errors.Is(err, ErrUnexpectedStatus) {
 				t.Fatalf("err = %v, want ErrUnexpectedStatus", err)
@@ -273,7 +302,8 @@ func TestFetchURIRateLimitThenError(t *testing.T) {
 		}
 		w.WriteHeader(http.StatusServiceUnavailable)
 	})
-	if _, err := ft.fetchURI(srv.URL, true); !errors.Is(err, ErrUnexpectedStatus) {
+	_, err := ft.fetchURI(srv.URL, true)
+	if !errors.Is(err, ErrUnexpectedStatus) {
 		t.Fatalf("err = %v, want ErrUnexpectedStatus", err)
 	}
 }
@@ -314,9 +344,13 @@ func TestFetchURIDebugTrace(t *testing.T) {
 	}
 	for name, mk := range handlers {
 		t.Run(name, func(t *testing.T) {
-			ft, _ := newTestFT(t, "debug", func(w http.ResponseWriter, r *http.Request) {
-				io.WriteString(w, packageJSON("", releaseJSON("ocds-1", "1")))
-			})
+			ft, _ := newTestFT(
+				t,
+				"debug",
+				func(w http.ResponseWriter, r *http.Request) {
+					io.WriteString(w, packageJSON("", releaseJSON("ocds-1", "1")))
+				},
+			)
 			var logs strings.Builder
 			quietLogs(t, mk(&logs))
 
@@ -343,8 +377,12 @@ func TestFetchURIDebugTrace(t *testing.T) {
 }
 
 func TestFetchURIDebugTraceConnectionError(t *testing.T) {
-	ft, srv := newTestFT(t, "debug", func(w http.ResponseWriter, r *http.Request) {
-	})
+	ft, srv := newTestFT(
+		t,
+		"debug",
+		func(w http.ResponseWriter, r *http.Request) {
+		},
+	)
 	srv.Close()
 	ft.httpClient.SetRetryCount(0)
 	if _, err := fetchURI(ft, srv.URL); err == nil {
@@ -419,13 +457,18 @@ func TestSafeUnpackReleases(t *testing.T) {
 			{"ocid": "ocds-3", "id": "3", "date": "2026-10-08", "tag": [], "initiationType": "tender"}
 		]
 	}`
+
 	pkg, err := safeUnpackReleases(slog.Default(), responseFor(t, body))
 	if err != nil {
 		t.Fatal(err)
 	}
-	if pkg.URI != "https://example/pkg" || pkg.Version != "1.1" || len(pkg.Extensions) != 1 ||
-		pkg.Publisher == nil || pkg.Publisher.Name != "FTS" || pkg.License != "OGL" ||
-		pkg.PublicationPolicy != "policy" || pkg.Links == nil || pkg.Links.Next != "https://example/next" {
+
+	copied := pkg.URI == "https://example/pkg" && pkg.Version == "1.1" &&
+		len(pkg.Extensions) == 1 && pkg.Publisher != nil &&
+		pkg.Publisher.Name == "FTS" && pkg.License == "OGL" &&
+		pkg.PublicationPolicy == "policy" && pkg.Links != nil &&
+		pkg.Links.Next == "https://example/next"
+	if !copied {
 		t.Errorf("package fields not copied: %+v", pkg)
 	}
 	if pkg.PublishedDate == nil ||
@@ -434,7 +477,9 @@ func TestSafeUnpackReleases(t *testing.T) {
 	}
 	if len(pkg.Releases) != 2 || pkg.Releases[0].OCID != "ocds-1" ||
 		pkg.Releases[1].OCID != "ocds-3" {
-		t.Errorf("releases = %+v, want ocds-1 and ocds-3 (bad one skipped)", pkg.Releases)
+		t.Errorf(
+			"releases = %+v, want ocds-1 and ocds-3 (bad one skipped)", pkg.Releases,
+		)
 	}
 }
 
@@ -446,8 +491,16 @@ func TestSafeUnpackReleasesPublishedDate(t *testing.T) {
 	}{
 		{"omitted", "", nil},
 		{"empty string", `""`, nil},
-		{"RFC3339", `"2026-10-08T12:00:00Z"`, ptrTime(time.Date(2026, 10, 8, 12, 0, 0, 0, time.UTC))},
-		{"date only", `"2026-10-08"`, ptrTime(time.Date(2026, 10, 8, 0, 0, 0, 0, time.UTC))},
+		{
+			"RFC3339",
+			`"2026-10-08T12:00:00Z"`,
+			ptrTime(time.Date(2026, 10, 8, 12, 0, 0, 0, time.UTC)),
+		},
+		{
+			"date only",
+			`"2026-10-08"`,
+			ptrTime(time.Date(2026, 10, 8, 0, 0, 0, 0, time.UTC)),
+		},
 		{"unparseable", `"yesterday"`, nil},
 	}
 	for _, tt := range tests {
@@ -463,7 +516,8 @@ func TestSafeUnpackReleasesPublishedDate(t *testing.T) {
 			switch {
 			case tt.want == nil && pkg.PublishedDate != nil:
 				t.Errorf("publishedDate = %v, want nil", pkg.PublishedDate)
-			case tt.want != nil && (pkg.PublishedDate == nil || !pkg.PublishedDate.Equal(*tt.want)):
+			case tt.want != nil && (pkg.PublishedDate == nil ||
+				!pkg.PublishedDate.Equal(*tt.want)):
 				t.Errorf("publishedDate = %v, want %v", pkg.PublishedDate, tt.want)
 			}
 		})
@@ -480,7 +534,9 @@ func TestSafeUnpackReleasesInvalidJSON(t *testing.T) {
 		"publisher array": `{"publisher": []}`,
 	} {
 		t.Run(name, func(t *testing.T) {
-			if _, err := safeUnpackReleases(slog.Default(), responseFor(t, body)); err == nil {
+			if _, err := safeUnpackReleases(
+				slog.Default(), responseFor(t, body),
+			); err == nil {
 				t.Error("expected a decode error")
 			}
 		})
@@ -489,18 +545,23 @@ func TestSafeUnpackReleasesInvalidJSON(t *testing.T) {
 
 // pagedServer serves pages[i] for ?page=i (page 0 at the release package
 // path), linking each page to the next.
-func pagedServer(t *testing.T, pages ...[]string) (*FindATender, *atomic.Int32) {
+func pagedServer(
+	t *testing.T, pages ...[]string,
+) (*FindATender, *atomic.Int32) {
 	t.Helper()
 	var hits atomic.Int32
 	var srvURL string
 	ft, srv := newTestFT(t, "warn", func(w http.ResponseWriter, r *http.Request) {
 		hits.Add(1)
+
 		i := 0
 		fmt.Sscan(r.URL.Query().Get("page"), &i)
+
 		next := ""
 		if i+1 < len(pages) {
 			next = fmt.Sprintf("%s/ocdsReleasePackages?page=%d", srvURL, i+1)
 		}
+
 		io.WriteString(w, packageJSON(next, pages[i]...))
 	})
 	srvURL = srv.URL
@@ -513,12 +574,14 @@ func TestFetchOnce(t *testing.T) {
 		[]string{releaseJSON("ocds-1", "1"), releaseJSON("ocds-2", "1")},
 		[]string{releaseJSON("ocds-3", "1")},
 	)
+
 	releases, err := ft.fetchOnce(RequestOptions{
 		Since: time.Now(),
 	})
 	if err != nil {
 		t.Fatal(err)
 	}
+
 	if len(releases) != 2 {
 		t.Errorf("got %d releases, want 2 (first page only)", len(releases))
 	}
@@ -551,10 +614,7 @@ func TestFetchOnceErrors(t *testing.T) {
 		RequestOptions{
 			Since: time.Now(),
 		},
-	); !errors.Is(
-		err,
-		ErrRateLimitExceeded,
-	) {
+	); !errors.Is(err, ErrRateLimitExceeded) {
 		t.Errorf("rate limited: err = %v, want ErrRateLimitExceeded", err)
 	}
 }
@@ -566,12 +626,14 @@ func TestFetchAll(t *testing.T) {
 		[]string{},
 		[]string{releaseJSON("ocds-1", "2")},
 	)
+
 	releases, err := ft.fetchAll(RequestOptions{
 		Since: time.Now(),
 	})
 	if err != nil {
 		t.Fatal(err)
 	}
+
 	var ids []string
 	for _, r := range releases {
 		ids = append(ids, r.OCID+"/"+r.ID)
@@ -600,10 +662,7 @@ func TestFetchAllErrors(t *testing.T) {
 		RequestOptions{
 			Since: time.Now(),
 		},
-	); !errors.Is(
-		err,
-		ErrRateLimitExceeded,
-	) {
+	); !errors.Is(err, ErrRateLimitExceeded) {
 		t.Errorf("first page rate limited: err = %v", err)
 	}
 
@@ -627,13 +686,19 @@ func TestFetchAllErrors(t *testing.T) {
 	} {
 		t.Run(name, func(t *testing.T) {
 			var srvURL string
-			ft, srv := newTestFT(t, "warn", func(w http.ResponseWriter, r *http.Request) {
-				if r.URL.Query().Get("page") == "" {
-					io.WriteString(w, packageJSON(srvURL+"/next?page=1", releaseJSON("ocds-1", "1")))
-					return
-				}
-				fail(w, r)
-			})
+			ft, srv := newTestFT(
+				t,
+				"warn",
+				func(w http.ResponseWriter, r *http.Request) {
+					if r.URL.Query().Get("page") == "" {
+						io.WriteString(
+							w, packageJSON(srvURL+"/next?page=1", releaseJSON("ocds-1", "1")),
+						)
+						return
+					}
+					fail(w, r)
+				},
+			)
 			srvURL = srv.URL
 			if _, err := ft.fetchAll(RequestOptions{
 				Since: time.Now(),
@@ -663,17 +728,22 @@ func TestFetchAllRepeatedNextLink(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			var hits atomic.Int32
 			var srvURL string
-			ft, srv := newTestFT(t, "error", func(w http.ResponseWriter, r *http.Request) {
-				if hits.Add(1) > 10 {
-					t.Error("fetchAll did not stop following next links")
-					w.WriteHeader(http.StatusBadRequest)
-					return
-				}
-				page := r.URL.Query().Get("page")
-				io.WriteString(w, packageJSON(
-					nextFor(srvURL, page), releaseJSON("ocds-"+page, "1"),
-				))
-			})
+			ft, srv := newTestFT(
+				t,
+				"error",
+				func(w http.ResponseWriter, r *http.Request) {
+					if hits.Add(1) > 10 {
+						t.Error("fetchAll did not stop following next links")
+						w.WriteHeader(http.StatusBadRequest)
+						return
+					}
+					page := r.URL.Query().Get("page")
+					body := packageJSON(
+						nextFor(srvURL, page), releaseJSON("ocds-"+page, "1"),
+					)
+					io.WriteString(w, body)
+				},
+			)
 			srvURL = srv.URL
 
 			releases, err := ft.fetchAll(RequestOptions{
@@ -683,7 +753,11 @@ func TestFetchAllRepeatedNextLink(t *testing.T) {
 				t.Fatal(err)
 			}
 			if len(releases) != int(hits.Load()) {
-				t.Errorf("releases = %d, want one per request (%d)", len(releases), hits.Load())
+				t.Errorf(
+					"releases = %d, want one per request (%d)",
+					len(releases),
+					hits.Load(),
+				)
 			}
 		})
 	}
@@ -730,23 +804,28 @@ func TestUnmarshalLenientDates(t *testing.T) {
 		t.Errorf("date = %v", got.Date)
 	}
 	if got.PublishedDate != nil {
-		t.Errorf("empty publishedDate should decode as nil, got %v", got.PublishedDate)
+		t.Errorf(
+			"empty publishedDate should decode as nil, got %v", got.PublishedDate,
+		)
 	}
+	wantStart := time.Date(2006, 10, 2, 15, 33, 2, 0, time.FixedZone("", 7*3600))
 	if start := got.Tender.TenderPeriod.StartDate; start == nil ||
-		!start.Equal(time.Date(2006, 10, 2, 15, 33, 2, 0, time.FixedZone("", 7*3600))) {
+		!start.Equal(wantStart) {
 		t.Errorf("full timestamp changed: %v", start)
 	}
-	if end := got.Tender.TenderPeriod.EndDate; end == nil || !end.Equal(midnight(2006, 11, 30)) {
+	if end := got.Tender.TenderPeriod.EndDate; end == nil ||
+		!end.Equal(midnight(2006, 11, 30)) {
 		t.Errorf("endDate = %v", end)
 	}
-	if d := got.Tender.ExpressionOfInterestDeadline; d == nil || !d.Equal(midnight(2006, 10, 20)) {
+	if d := got.Tender.ExpressionOfInterestDeadline; d == nil ||
+		!d.Equal(midnight(2006, 10, 20)) {
 		t.Errorf("expressionOfInterestDeadline = %v", d)
 	}
 	if got.Tender.Description != "Bids close on 2006-11-30" {
 		t.Errorf("free text changed: %q", got.Tender.Description)
 	}
-	if a := got.Awards[0]; a.Date == nil || !a.Date.Equal(midnight(2006, 12, 1)) ||
-		a.ID != "2006-12-01" {
+	if a := got.Awards[0]; a.Date == nil ||
+		!a.Date.Equal(midnight(2006, 12, 1)) || a.ID != "2006-12-01" {
 		t.Errorf("award = %+v (date should be repaired, id left alone)", a)
 	}
 	if got.Value != "1234567.891" {
@@ -829,9 +908,27 @@ func TestReleaseIDs(t *testing.T) {
 		{"missing ocid", `{"id":"r1"}`, "", "r1", "no ocid"},
 		{"missing id", `{"ocid":"ocds-1"}`, "ocds-1", "", "no id"},
 		{"ocid wrong type", `{"ocid":5,"id":"r1"}`, "", "", "reading release ocid"},
-		{"id wrong type", `{"ocid":"ocds-1","id":true}`, "ocds-1", "", "unexpected bool"},
-		{"id is an object", `{"ocid":"ocds-1","id":{}}`, "ocds-1", "", "unexpected map"},
-		{"invalid id JSON", `{"ocid":"ocds-1","id":}`, "ocds-1", "", "reading release id"},
+		{
+			"id wrong type",
+			`{"ocid":"ocds-1","id":true}`,
+			"ocds-1",
+			"",
+			"unexpected bool",
+		},
+		{
+			"id is an object",
+			`{"ocid":"ocds-1","id":{}}`,
+			"ocds-1",
+			"",
+			"unexpected map",
+		},
+		{
+			"invalid id JSON",
+			`{"ocid":"ocds-1","id":}`,
+			"ocds-1",
+			"",
+			"reading release id",
+		},
 		{
 			"invalid field before ids",
 			`{"date":nope,"ocid":"ocds-1","id":"r1"}`,
@@ -839,7 +936,13 @@ func TestReleaseIDs(t *testing.T) {
 			"",
 			`reading release field "date"`,
 		},
-		{"truncated after ocid", `{"ocid":"ocds-1",`, "ocds-1", "", "reading release"},
+		{
+			"truncated after ocid",
+			`{"ocid":"ocds-1",`,
+			"ocds-1",
+			"",
+			"reading release",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -852,7 +955,9 @@ func TestReleaseIDs(t *testing.T) {
 				t.Fatalf("err = %v, want containing %q", err, tt.wantErr)
 			}
 			if ocid != tt.wantOCID || id != tt.wantID {
-				t.Errorf("got (%q, %q), want (%q, %q)", ocid, id, tt.wantOCID, tt.wantID)
+				t.Errorf(
+					"got (%q, %q), want (%q, %q)", ocid, id, tt.wantOCID, tt.wantID,
+				)
 			}
 		})
 	}