build log --follow, streamed to the build page !462

merged merged by cmc on 2026-09-23 06:40 UTC · krz/gitbay:build-log-follow into main

27 files changed, +2118 −38

Layout: unified · split

.gitbay/wiki/Admin.org +4

 trusted proxy; from anyone else the header is ignored. Empty, the
 default, is right when gitbayd terminates TLS itself.
+A reverse proxy in front of gitbay must not buffer responses, or the
+build page's live log arrives only when the build ends;
+=X-Accel-Buffering: no= covers nginx.
 ** [web]
 - =mode= — =view_only= (default) | =accounts=. In view_only the mutating
   web routes are never registered; in accounts, browser sessions are

.gitbay/wiki/CI.org +11

	@@ -38,6 +38,17 @@ Scheduled jobs run on their cron against the default branch, never on
38	push; a default-branch push registers or updates them. Tag jobs run on	38	push; a default-branch push registers or updates them. Tag jobs run on
39	a matching tag push and nothing else.	39	a matching tag push and nothing else.
40		40
		41	A running build is followed with =build log <owner/name> <n> --follow=:
		42	the stored log, then output as the runner sends it, then the outcome
		43	as =build <n> <status>= on stderr once the build ends. The exit code is
		44	0 whatever the outcome. A follow of a build still queued after ten
		45	minutes ends on its own and says so on stderr, since nothing reaps a
		46	queued build. The build page does the same without JavaScript while a
		47	build is queued or running; =?follow=0= renders it once. An account
		48	holds at most eight follows open, and signed-out viewers share one
		49	account's eight. Over the JSON API the command answers when the build
		50	ends, with the whole log.
		51
41	* The table	52	* The table
42		53
43	One =ci.yml= with five jobs, each isolating one rule:	54	One =ci.yml= with five jobs, each isolating one rule:

.gitbay/wiki/Parity.org +1

	@@ -210,6 +210,7 @@ rather than the one the web page shows.
210	\| build list filters (ref, status, job) \| yes \| yes \| yes \|	210	\| build list filters (ref, status, job) \| yes \| yes \| yes \|
211	\| build show (one build) \| yes \| yes \| yes \|	211	\| build show (one build) \| yes \| yes \| yes \|
212	\| build log \| yes \| yes \| yes \|	212	\| build log \| yes \| yes \| yes \|
		213	\| build log follow (until it ends) \| yes \| yes \| no \|
213	\| build jobs \| yes \| yes \| yes \|	214	\| build jobs \| yes \| yes \| yes \|
214	\| build trigger \| yes \| yes \| yes \|	215	\| build trigger \| yes \| yes \| yes \|
215	\| build cancel \| yes \| yes \| yes \|	216	\| build cancel \| yes \| yes \| yes \|

cmd/gitbay/main.go +1 −1

	@@ -48,7 +48,7 @@ func newRoot() *cobra.Command {
48	group("build", "CI builds",	48	group("build", "CI builds",
49	pass("list", "recent builds: <owner/name>", passOpts{server: []string{"build", "list"}, needsRepo: true}),	49	pass("list", "recent builds: <owner/name>", passOpts{server: []string{"build", "list"}, needsRepo: true}),
50	pass("show", "one build: <owner/name> <n>", passOpts{server: []string{"build", "show"}, needsRepo: true}),	50	pass("show", "one build: <owner/name> <n>", passOpts{server: []string{"build", "show"}, needsRepo: true}),
51	pass("log", "a build's log: <owner/name> <n>", passOpts{server: []string{"build", "log"}, needsRepo: true}),	51	pass("log", "a build's log: <owner/name> <n> [--follow]", passOpts{server: []string{"build", "log"}, needsRepo: true}),
52	pass("jobs", "list the jobs a trigger can name", passOpts{server: []string{"build", "jobs"}, needsRepo: true}),	52	pass("jobs", "list the jobs a trigger can name", passOpts{server: []string{"build", "jobs"}, needsRepo: true}),
53	pass("trigger", "queue a job now: <job>", passOpts{server: []string{"build", "trigger"}, needsRepo: true}),	53	pass("trigger", "queue a job now: <job>", passOpts{server: []string{"build", "trigger"}, needsRepo: true}),
54	pass("cancel", "withdraw a queued build: <n>", passOpts{server: []string{"build", "cancel"}, needsRepo: true}),	54	pass("cancel", "withdraw a queued build: <n>", passOpts{server: []string{"build", "cancel"}, needsRepo: true}),

cmd/gitbayd/system.go +1 −1

	@@ -93,7 +93,7 @@ func shellCmd() *cobra.Command {
93	fmt.Fprintf(os.Stderr, "gitbay control plane: interactive shells are not available.\nTry: ssh <host> help\n")	93	fmt.Fprintf(os.Stderr, "gitbay control plane: interactive shells are not available.\nTry: ssh <host> help\n")
94	os.Exit(protocol.ExitUsage)	94	os.Exit(protocol.ExitUsage)
95	}	95	}
96	code := sshd.Exec(cfg, st, user, key.Scope, key.Fingerprint, cmdline, os.Stdin, os.Stdout, os.Stderr)	96	code := sshd.Exec(cfg, st, user, key.Scope, key.Fingerprint, cmdline, os.Stdin, os.Stdout, os.Stderr, nil)
97	st.Close()	97	st.Close()
98	os.Exit(code)	98	os.Exit(code)
99	return nil	99	return nil

docs/plans/2026-09-23-build-log-follow.md added +1100

@@ -0,0 +1,1100 @@
	1	# build log --follow Implementation Plan
	2
	3	> For agentic workers: REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
	4
	5	Goal: `build log <owner/name> <n> --follow` streams a build's log until the build has an outcome, and the web build page streams the same command without JavaScript.
	6
	7	Architecture: The store wakes waiters when a build's row changes and reads the log from a byte offset. The control command loops read → write → wait. The web handler renders `build.html` with a marker where the log goes, writes the part before it, dispatches the command with a writer that HTML-escapes and flushes, then writes the rest.
	8
	9	Tech Stack: Go, SQLite (modernc), `golang.org/x/crypto/ssh`, `html/template`, `net/http`.
	10
	11	Spec: `docs/specs/2026-09-23-build-log-follow-design.md`
	12
	13	## Global Constraints
	14
	15	- Work in `/Users/cmc/git/krz/gitbay-follow` (branch `build-log-follow`). Never touch `/Users/cmc/git/krz/gitbay`.
	16	- Every commit is signed (the repo signs by config; do not pass `--no-gpg-sign`). Messages reference `Ref #250`; the last commit says `Closes #250`. No attribution lines of any kind.
	17	- Write files with the editor tool, not heredocs.
	18	- Locally run: `go build ./...`, `go vet` on touched packages, unit tests of touched packages, and only the one e2e test being written. CI runs the rest.
	19	- Comments: plain, factual, match the surrounding density. No before/after narration.
	20	- Follow cap: 8 per account. Fallback re-read: 2 seconds. Settle after an outcome: 1 second.
	21	- The outcome line on stderr is exactly `build <n> <status>`; exit 0 whatever the outcome.
	22	- The web outcome line is exactly `<p class="notice" role="status">build finished: <status></p>`.
	23
	24	---
	25
	26	### Task 1: Store — wake followers and read from an offset
	27
	28	Files:
	29	- Modify: `internal/store/store.go` (the `Store` struct, ~line 22)
	30	- Modify: `internal/store/builds.go` (`AppendBuildLog` ~228, `FinishBuild` ~248, `CancelBuild` ~393; new functions after `BuildLog` ~325)
	31	- Test: `internal/store/builds_test.go`
	32
	33	Interfaces:
	34	- Produces: `func (s Store) BuildLogWait(id int64) <-chan struct{}`; `func (s Store) BuildLogFrom(id, offset int64) (status string, chunk []byte, err error)`; unexported `func (s *Store) wakeBuild(id int64)`.
	35
	36	- [ ] Step 1: Write the failing tests — append to `internal/store/builds_test.go`:
	37
	38	```go
	39	// A follower's channel closes on each kind of change to its build, and
	40	// only its build.
	41	func TestBuildLogWaitWakes(t *testing.T) {
	42	s := open(t)
	43	if err := s.MigrateUp(); err != nil {
	44	t.Fatal(err)
	45	}
	46	uid, err := s.CreateUser("cmc", true)
	47	if err != nil {
	48	t.Fatal(err)
	49	}
	50	if _, err := s.CreateRepo("user", uid, "orgo", "public"); err != nil {
	51	t.Fatal(err)
	52	}
	53	newBuild := func() int64 {
	54	t.Helper()
	55	id, err := s.CreateBuild(1, "test", "abc123", "main", `["true"]`, "", "", true)
	56	if err != nil {
	57	t.Fatal(err)
	58	}
	59	return id
	60	}
	61	closed := func(ch <-chan struct{}) bool {
	62	select {
	63	case <-ch:
	64	return true
	65	default:
	66	return false
	67	}
	68	}
	69
	70	a, b := newBuild(), newBuild()
	71	wa, wb := s.BuildLogWait(a), s.BuildLogWait(b)
	72	if err := s.AppendBuildLog(a, []byte("x")); err != nil {
	73	t.Fatal(err)
	74	}
	75	if !closed(wa) {
	76	t.Error("append did not wake its build")
	77	}
	78	if closed(wb) {
	79	t.Error("append woke another build")
	80	}
	81
	82	mustClaim(t, s, 1) // claims a, the oldest
	83	wa = s.BuildLogWait(a)
	84	if err := s.FinishBuild(a, "success"); err != nil {
	85	t.Fatal(err)
	86	}
	87	if !closed(wa) {
	88	t.Error("finish did not wake")
	89	}
	90
	91	if err := s.CancelBuild(b); err != nil {
	92	t.Fatal(err)
	93	}
	94	if !closed(wb) {
	95	t.Error("cancel did not wake")
	96	}
	97	}
	98
	99	// Offsets are bytes, not characters: \|\| stores the log as text, and a
	100	// multibyte character must not shift where the next read starts.
	101	func TestBuildLogFrom(t *testing.T) {
	102	s := open(t)
	103	if err := s.MigrateUp(); err != nil {
	104	t.Fatal(err)
	105	}
	106	uid, err := s.CreateUser("cmc", true)
	107	if err != nil {
	108	t.Fatal(err)
	109	}
	110	if _, err := s.CreateRepo("user", uid, "orgo", "public"); err != nil {
	111	t.Fatal(err)
	112	}
	113	id, err := s.CreateBuild(1, "test", "abc123", "main", `["true"]`, "", "", true)
	114	if err != nil {
	115	t.Fatal(err)
	116	}
	117	first := "héllo — ok\n"
	118	for _, c := range []string{first, "wörld\n"} {
	119	if err := s.AppendBuildLog(id, []byte(c)); err != nil {
	120	t.Fatal(err)
	121	}
	122	}
	123	status, all, err := s.BuildLogFrom(id, 0)
	124	if err != nil \|\| status != "pending" \|\| string(all) != first+"wörld\n" {
	125	t.Fatalf("from 0: %q %q %v", status, all, err)
	126	}
	127	_, rest, err := s.BuildLogFrom(id, int64(len(first)))
	128	if err != nil \|\| string(rest) != "wörld\n" {
	129	t.Fatalf("from %d: %q %v", len(first), rest, err)
	130	}
	131	_, none, err := s.BuildLogFrom(id, int64(len(all)))
	132	if err != nil \|\| len(none) != 0 {
	133	t.Fatalf("from the end: %q %v", none, err)
	134	}
	135	if _, _, err := s.BuildLogFrom(9999, 0); err != ErrNotFound {
	136	t.Fatalf("missing build: %v", err)
	137	}
	138	}
	139	```
	140
	141	- [ ] Step 2: Run to see them fail
	142
	143	Run: `go test ./internal/store/ -run 'TestBuildLogWaitWakes\|TestBuildLogFrom' -count=1`
	144	Expected: build failure, `s.BuildLogWait undefined`.
	145
	146	- [ ] Step 3: Implement
	147
	148	In `internal/store/store.go`, add `"sync"` to the imports and the fields:
	149
	150	```go
	151	type Store struct {
	152	DB *sql.DB
	153
	154	// logWait holds one channel per build someone is following, closed
	155	// by the next change to that build's row (BuildLogWait).
	156	logMu sync.Mutex
	157	logWait map[int64]chan struct{}
	158	}
	159	```
	160
	161	In `internal/store/builds.go`, after `BuildLog`:
	162
	163	```go
	164	// BuildLogWait returns a channel closed by the next append to, finish of
	165	// or cancel of the build. Take it before reading, so a change between the
	166	// read and the wait still wakes the reader. Only this process's writes
	167	// wake it.
	168	func (s *Store) BuildLogWait(id int64) <-chan struct{} {
	169	s.logMu.Lock()
	170	defer s.logMu.Unlock()
	171	if s.logWait == nil {
	172	s.logWait = map[int64]chan struct{}{}
	173	}
	174	ch, ok := s.logWait[id]
	175	if !ok {
	176	ch = make(chan struct{})
	177	s.logWait[id] = ch
	178	}
	179	return ch
	180	}
	181
	182	func (s *Store) wakeBuild(id int64) {
	183	s.logMu.Lock()
	184	defer s.logMu.Unlock()
	185	if ch, ok := s.logWait[id]; ok {
	186	close(ch)
	187	delete(s.logWait, id)
	188	}
	189	}
	190
	191	// BuildLogFrom returns the build's status and its log past offset bytes,
	192	// read together so a terminal status comes with every byte before it.
	193	// The cast matters: \|\| stores the log as text, and substr on text counts
	194	// characters.
	195	func (s *Store) BuildLogFrom(id, offset int64) (string, []byte, error) {
	196	var status string
	197	var chunk []byte
	198	err := s.DB.QueryRow(`SELECT status, substr(CAST(log AS BLOB), ?) FROM builds WHERE id = ?`,
	199	offset+1, id).Scan(&status, &chunk)
	200	if errors.Is(err, sql.ErrNoRows) {
	201	return "", nil, ErrNotFound
	202	}
	203	return status, chunk, err
	204	}
	205	```
	206
	207	Wake after each successful write. In `AppendBuildLog`, replace the tail so both paths wake:
	208
	209	```go
	210	if n, _ := res.RowsAffected(); n > 0 {
	211	s.wakeBuild(id)
	212	return nil
	213	}
	214	// Over the cap. The bounds match exactly once: appending the notice puts
	215	// the log past the upper bound, so later chunks fall through silently.
	216	_, err = s.DB.Exec(`
	217	UPDATE builds SET log = log \|\| ?
	218	WHERE id = ? AND length(log) >= ? AND length(log) < ?`,
	219	truncNotice, id, MaxBuildLog, MaxBuildLog+len(truncNotice))
	220	if err == nil {
	221	s.wakeBuild(id)
	222	}
	223	return err
	224	```
	225
	226	In `FinishBuild`, before the final `return nil`: `s.wakeBuild(id)`. In `CancelBuild`, the same, before its final `return nil`.
	227
	228	- [ ] Step 4: Run the tests and vet
	229
	230	Run: `go test ./internal/store/ -count=1 && go vet ./internal/store/`
	231	Expected: `ok`, vet silent (no copylocks: `Store` is only ever `&Store{...}` in `Open`).
	232
	233	- [ ] Step 5: Commit
	234
	235	```bash
	236	git add internal/store/store.go internal/store/builds.go internal/store/builds_test.go
	237	git commit -m "store: wake build log followers, read the log from an offset
	238
	239	Ref #250"
	240	```
	241
	242	---
	243
	244	### Task 2: Control — `build log --follow`
	245
	246	Files:
	247	- Modify: `internal/control/control.go` (`Ctx`, ~line 21)
	248	- Modify: `internal/control/build.go` (registration ~29, `runBuildLog` ~198)
	249	- Create: `internal/control/buildfollow.go`
	250	- Create: `internal/control/buildfollow_test.go`
	251	- Modify: `cmd/gitbay/main.go:51` (help string)
	252
	253	Interfaces:
	254	- Consumes: `Store.BuildLogWait`, `Store.BuildLogFrom` (Task 1).
	255	- Produces: `Ctx.Done <-chan struct{}`; the command `build log <owner/name> <n> [--follow]`; package vars `followSettle`, `followPoll` (tests shorten them); `maxFollows = 8`.
	256
	257	- [ ] Step 1: Write the failing tests — `internal/control/buildfollow_test.go`:
	258
	259	```go
	260	package control
	261
	262	import (
	263	"bytes"
	264	"strings"
	265	"testing"
	266	"time"
	267
	268	"gitbay.org/gitbay/internal/protocol"
	269	"gitbay.org/gitbay/internal/store"
	270	)
	271
	272	// follow starts build log --follow on build 1 of repo and returns the
	273	// buffers and a channel carrying the exit code.
	274	func follow(t testing.T, st store.Store, uid int64, repo store.Repo, done <-chan struct{}) (bytes.Buffer, bytes.Buffer, chan int) {
	275	t.Helper()
	276	u, err := st.UserByID(uid)
	277	if err != nil {
	278	t.Fatal(err)
	279	}
	280	var out, errOut bytes.Buffer
	281	c := &Ctx{User: u, Scope: "full", Store: st, Stdin: strings.NewReader(""),
	282	Stdout: &out, Stderr: &errOut, Done: done}
	283	res := make(chan int, 1)
	284	go func() { res <- Dispatch(c, []string{"build", "log", repo.Path(), "1", "--follow"}) }()
	285	return &out, &errOut, res
	286	}
	287
	288	func waitExit(t *testing.T, res chan int) int {
	289	t.Helper()
	290	select {
	291	case code := <-res:
	292	return code
	293	case <-time.After(10 * time.Second):
	294	t.Fatal("follow did not end")
	295	return -1
	296	}
	297	}
	298
	299	func shortFollowTimers(t *testing.T) {
	300	settle, poll := followSettle, followPoll
	301	followSettle, followPoll = 200time.Millisecond, 50time.Millisecond
	302	t.Cleanup(func() { followSettle, followPoll = settle, poll })
	303	}
	304
	305	// The follow prints the stored log, then what arrives, and ends with the
	306	// outcome on stderr once the build finishes.
	307	func TestBuildLogFollow(t *testing.T) {
	308	shortFollowTimers(t)
	309	st, repo, uid := newQueueTestRepo(t)
	310	id, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true)
	311	if err != nil {
	312	t.Fatal(err)
	313	}
	314	st.AppendBuildLog(id, []byte("queued\n"))
	315	out, errOut, res := follow(t, st, uid, repo, nil)
	316
	317	if _, ok, err := st.ClaimBuild([]int64{repo.ID}, false); err != nil \|\| !ok {
	318	t.Fatalf("claim: %v %v", ok, err)
	319	}
	320	st.AppendBuildLog(id, []byte("step one\n"))
	321	st.AppendBuildLog(id, []byte("step two\n"))
	322	if err := st.FinishBuild(id, "success"); err != nil {
	323	t.Fatal(err)
	324	}
	325	if code := waitExit(t, res); code != protocol.ExitOK {
	326	t.Fatalf("exit %d: %s", code, errOut)
	327	}
	328	if got := out.String(); got != "queued\nstep one\nstep two\n" {
	329	t.Errorf("stdout %q", got)
	330	}
	331	if got := strings.TrimSpace(errOut.String()); got != "build 1 success" {
	332	t.Errorf("stderr %q", got)
	333	}
	334	}
	335
	336	// A cancel ends the follow, and the line the cancel appends after the
	337	// status change still arrives.
	338	func TestBuildLogFollowCancel(t *testing.T) {
	339	shortFollowTimers(t)
	340	st, repo, uid := newQueueTestRepo(t)
	341	id, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true)
	342	if err != nil {
	343	t.Fatal(err)
	344	}
	345	out, errOut, res := follow(t, st, uid, repo, nil)
	346	if err := st.CancelBuild(id); err != nil {
	347	t.Fatal(err)
	348	}
	349	st.AppendBuildLog(id, []byte("cancelled by alice before a runner claimed it\n"))
	350	if code := waitExit(t, res); code != protocol.ExitOK {
	351	t.Fatalf("exit %d: %s", code, errOut)
	352	}
	353	if !strings.Contains(out.String(), "cancelled by alice") {
	354	t.Errorf("the cancel line did not arrive: %q", out)
	355	}
	356	if got := strings.TrimSpace(errOut.String()); got != "build 1 cancelled" {
	357	t.Errorf("stderr %q", got)
	358	}
	359	}
	360
	361	// Closing Done ends a follow of a build that is still running.
	362	func TestBuildLogFollowDone(t *testing.T) {
	363	shortFollowTimers(t)
	364	st, repo, uid := newQueueTestRepo(t)
	365	if _, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true); err != nil {
	366	t.Fatal(err)
	367	}
	368	done := make(chan struct{})
	369	_, _, res := follow(t, st, uid, repo, done)
	370	close(done)
	371	if code := waitExit(t, res); code != protocol.ExitFailure {
	372	t.Fatalf("exit %d, want %d", code, protocol.ExitFailure)
	373	}
	374	}
	375
	376	// An account holding maxFollows is refused another.
	377	func TestBuildLogFollowCap(t *testing.T) {
	378	st, repo, uid := newQueueTestRepo(t)
	379	if _, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true); err != nil {
	380	t.Fatal(err)
	381	}
	382	followMu.Lock()
	383	follows[uid] = maxFollows
	384	followMu.Unlock()
	385	t.Cleanup(func() {
	386	followMu.Lock()
	387	delete(follows, uid)
	388	followMu.Unlock()
	389	})
	390	_, errOut, res := follow(t, st, uid, repo, nil)
	391	if code := waitExit(t, res); code != protocol.ExitDenied {
	392	t.Fatalf("exit %d, want %d", code, protocol.ExitDenied)
	393	}
	394	if !strings.Contains(errOut.String(), "8 follows are already open") {
	395	t.Errorf("stderr %q", errOut)
	396	}
	397	}
	398	```
	399
	400	- [ ] Step 2: Run to see them fail
	401
	402	Run: `go test ./internal/control/ -run 'TestBuildLogFollow' -count=1`
	403	Expected: build failure, `unknown field Done` / `undefined: followSettle`.
	404
	405	- [ ] Step 3: Implement
	406
	407	`internal/control/control.go`, in `Ctx` after `Cmd`:
	408
	409	```go
	410	// Done, when the surface has one, closes when nobody is reading any
	411	// more: the SSH channel closed or the HTTP request ended. A command
	412	// that runs until something happens (build log --follow) stops on it.
	413	Done <-chan struct{}
	414	```
	415
	416	`internal/control/build.go` registration:
	417
	418	```go
	419	register(Command{Path: []string{"build", "log"},
	420	Summary: "print a build's log, or follow it until the build ends",
	421	Usage: "build log <owner/name> <n> [--follow]", ReadOnly: true, Run: runBuildLog})
	422	```
	423
	424	`runBuildLog`:
	425
	426	```go
	427	func runBuildLog(c *Ctx, args []string) int {
	428	f, err := parseFlags(args, flagSpec{Bools: []string{"--follow"}, MaxPos: 2, Usage: c.Cmd.Usage})
	429	if err != nil {
	430	return c.fail(protocol.ExitUsage, "%v", err)
	431	}
	432	_, b, code := buildRef(c, f.Pos)
	433	if code >= 0 {
	434	return code
	435	}
	436	if f.Has("--follow") {
	437	return followBuildLog(c, b)
	438	}
	439	log, err := c.Store.BuildLog(b.ID)
	440	if err != nil {
	441	return c.fail(protocol.ExitFailure, "%v", err)
	442	}
	443	c.Stdout.Write(log)
	444	return protocol.ExitOK
	445	}
	446	```
	447
	448	Check how `runBuildList` (build.go ~125) reports a `parseFlags` error and match it exactly if it differs from the above.
	449
	450	`internal/control/buildfollow.go`:
	451
	452	```go
	453	package control
	454
	455	import (
	456	"fmt"
	457	"sync"
	458	"time"
	459
	460	"gitbay.org/gitbay/internal/protocol"
	461	"gitbay.org/gitbay/internal/store"
	462	)
	463
	464	// maxFollows is how many build log follows one account holds open at
	465	// once. Signed-out web viewers are account 0 and share it.
	466	const maxFollows = 8
	467
	468	var (
	469	// followPoll bounds a wait with no wake. A write from another process
	470	// (gitbayd admin, or any session under gitbayd shell) wakes nobody;
	471	// this is how its bytes still arrive.
	472	followPoll = 2 * time.Second
	473	// followSettle is how long a follow keeps reading after the build has
	474	// an outcome: a cancel appends its line after the status changes, and
	475	// a cancelled runner's stream runs on until its next check.
	476	followSettle = time.Second
	477	)
	478
	479	var (
	480	followMu sync.Mutex
	481	follows = map[int64]int{}
	482	)
	483
	484	func takeFollow(uid int64) bool {
	485	followMu.Lock()
	486	defer followMu.Unlock()
	487	if follows[uid] >= maxFollows {
	488	return false
	489	}
	490	follows[uid]++
	491	return true
	492	}
	493
	494	func dropFollow(uid int64) {
	495	followMu.Lock()
	496	defer followMu.Unlock()
	497	if follows[uid]--; follows[uid] <= 0 {
	498	delete(follows, uid)
	499	}
	500	}
	501
	502	// followBuildLog writes the build's log as it grows and returns once the
	503	// build has an outcome and its last bytes are written. The outcome goes
	504	// to stderr, so stdout is the log byte for byte.
	505	func followBuildLog(c *Ctx, b store.Build) int {
	506	if !takeFollow(c.User.ID) {
	507	return c.fail(protocol.ExitDenied, "%d follows are already open for this account; close one and retry", maxFollows)
	508	}
	509	defer dropFollow(c.User.ID)
	510
	511	var off int64
	512	var settleBy time.Time
	513	for {
	514	wake := c.Store.BuildLogWait(b.ID)
	515	status, chunk, err := c.Store.BuildLogFrom(b.ID, off)
	516	if err != nil {
	517	return c.fail(protocol.ExitFailure, "%v", err)
	518	}
	519	if len(chunk) > 0 {
	520	if _, err := c.Stdout.Write(chunk); err != nil {
	521	return protocol.ExitFailure
	522	}
	523	off += int64(len(chunk))
	524	}
	525	wait := followPoll
	526	if status != "pending" && status != "running" {
	527	if settleBy.IsZero() {
	528	settleBy = time.Now().Add(followSettle)
	529	}
	530	left := time.Until(settleBy)
	531	if left <= 0 && len(chunk) == 0 {
	532	fmt.Fprintf(c.Stderr, "build %d %s\n", b.Number, status)
	533	return protocol.ExitOK
	534	}
	535	wait = min(wait, max(left, 0))
	536	}
	537	t := time.NewTimer(wait)
	538	select {
	539	case <-wake:
	540	case <-t.C:
	541	case <-c.Done:
	542	t.Stop()
	543	return protocol.ExitFailure
	544	}
	545	t.Stop()
	546	}
	547	}
	548	```
	549
	550	Check the loop against the spec before moving on: once the status is terminal it keeps reading until `followSettle` has passed and a read came back empty, then prints the outcome. A deadline, not a `time.After` channel: a timer channel delivers once, and a second check of it would block. A nil `c.Done` never fires in the select, which is what a surface without one wants. `min`/`max` are Go 1.21 builtins; check `go.mod`'s go line is at least 1.21.
	551
	552	`cmd/gitbay/main.go:51`:
	553
	554	```go
	555	pass("log", "a build's log: <owner/name> <n> [--follow]", passOpts{server: []string{"build", "log"}, needsRepo: true}),
	556	```
	557
	558	- [ ] Step 4: Run the tests, the race detector, and vet
	559
	560	Run: `go test ./internal/control/ -run 'TestBuildLog' -count=1 -race && go vet ./internal/control/ ./cmd/gitbay/ && go test ./cmd/gitbay/ -count=1`
	561	Expected: `ok` for each.
	562
	563	Then run the whole control package once, since `build log` is covered elsewhere too: `go test ./internal/control/ -count=1`.
	564
	565	- [ ] Step 5: Commit
	566
	567	```bash
	568	git add internal/control/control.go internal/control/build.go internal/control/buildfollow.go internal/control/buildfollow_test.go cmd/gitbay/main.go
	569	git commit -m "build log --follow: stream a build's log until it ends
	570
	571	Ref #250"
	572	```
	573
	574	---
	575
	576	### Task 3: Surfaces pass Done — SSH channel close, HTTP request end
	577
	578	Files:
	579	- Modify: `internal/sshd/sshd.go` (`handleSession` ~230, `runExec` ~270, `Exec` ~305, the `control.Ctx` at ~335)
	580	- Modify: `cmd/gitbayd/system.go:96`
	581	- Modify: `internal/httpd/api.go` (~64), `internal/httpd/apiread.go` (~53)
	582
	583	Interfaces:
	584	- Consumes: `Ctx.Done` (Task 2).
	585	- Produces: `sshd.Exec(cfg, st, user, scope, source, cmdline string, stdin io.Reader, stdout, stderr io.Writer, done <-chan struct{}) int`.
	586
	587	- [ ] Step 1: SSH. In `handleSession`'s `"exec"` case, replace the two lines after `req.Reply(true, nil)`:
	588
	589	```go
	590	req.Reply(true, nil)
	591	// x/crypto closes reqs when the client closes the channel. That
	592	// is how a follow learns nobody is reading: the CLI's shared
	593	// connection outlives a Ctrl-C, the channel does not.
	594	done := make(chan struct{})
	595	go func() {
	596	for r := range reqs {
	597	r.Reply(false, nil)
	598	}
	599	close(done)
	600	}()
	601	code := s.runExec(sconn, ch, payload.Command, done)
	602	sendExit(ch, code)
	603	return
	604	```
	605
	606	`runExec` gains `done <-chan struct{}` as its last parameter and passes it to `Exec`. `Exec` gains `done <-chan struct{}` as its last parameter and sets `Done: done` in the `control.Ctx` it builds. `cmd/gitbayd/system.go:96` passes `nil` (that process ends with its session).
	607
	608	Find every other caller: `grep -rn 'sshd.Exec(\\|\.runExec(' --include='*.go' .` and update them, test files included.
	609
	610	- [ ] Step 2: API. In `internal/httpd/api.go` and `internal/httpd/apiread.go`, add `Done: r.Context().Done(),` to the `control.Ctx` literal.
	611
	612	- [ ] Step 3: Build, vet, test
	613
	614	Run: `go build ./... && go vet ./internal/sshd/ ./internal/httpd/ ./cmd/gitbayd/ && go test ./internal/sshd/ ./internal/httpd/ -count=1`
	615	Expected: `ok`.
	616
	617	- [ ] Step 4: Commit
	618
	619	```bash
	620	git add internal/sshd/sshd.go cmd/gitbayd/system.go internal/httpd/api.go internal/httpd/apiread.go
	621	git commit -m "sshd, api: end a command when its reader goes away
	622
	623	Ref #250"
	624	```
	625
	626	---
	627
	628	### Task 4: gzipWriter passes a flush through
	629
	630	Files:
	631	- Modify: `internal/httpd/compress.go`
	632	- Test: `internal/httpd/compress_test.go`
	633
	634	Interfaces:
	635	- Produces: `(gzipWriter).Flush()`, `(gzipWriter).Unwrap() http.ResponseWriter`.
	636
	637	- [ ] Step 1: Write the failing test — append to `internal/httpd/compress_test.go` (add missing imports: `bytes`, `compress/gzip`, `io`, `net/http`, `net/http/httptest`, `strings`):
	638
	639	```go
	640	// A flush mid-response reaches the connection with what was written so
	641	// far decodable, which is what lets a page stream through gzip.
	642	func TestGzipWriterFlushes(t *testing.T) {
	643	rec := httptest.NewRecorder()
	644	h := compressed(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	645	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	646	io.WriteString(w, "<p>first</p>")
	647	if err := http.NewResponseController(w).Flush(); err != nil {
	648	t.Fatalf("flush: %v", err)
	649	}
	650	if !rec.Flushed {
	651	t.Fatal("the flush did not reach the connection")
	652	}
	653	zr, err := gzip.NewReader(bytes.NewReader(rec.Body.Bytes()))
	654	if err != nil {
	655	t.Fatalf("gzip header: %v", err)
	656	}
	657	got, _ := io.ReadAll(zr) // no trailer yet: ends in ErrUnexpectedEOF
	658	if !strings.Contains(string(got), "<p>first</p>") {
	659	t.Fatalf("flushed body decodes to %q", got)
	660	}
	661	io.WriteString(w, "<p>second</p>")
	662	}))
	663	req := httptest.NewRequest("GET", "/", nil)
	664	req.Header.Set("Accept-Encoding", "gzip")
	665	h.ServeHTTP(rec, req)
	666	}
	667	```
	668
	669	- [ ] Step 2: Run to see it fail
	670
	671	Run: `go test ./internal/httpd/ -run TestGzipWriterFlushes -count=1`
	672	Expected: FAIL, `flush: feature not supported`.
	673
	674	- [ ] Step 3: Implement — in `internal/httpd/compress.go`, after `Close`:
	675
	676	```go
	677	// Flush sends what the gzip stream holds, then flushes the connection, so
	678	// a streamed page reaches the browser as it is written.
	679	func (g *gzipWriter) Flush() {
	680	if !g.decided {
	681	g.decide(http.StatusOK)
	682	}
	683	if g.gz != nil {
	684	g.gz.Flush()
	685	}
	686	http.NewResponseController(g.ResponseWriter).Flush()
	687	}
	688
	689	func (g *gzipWriter) Unwrap() http.ResponseWriter { return g.ResponseWriter }
	690	```
	691
	692	- [ ] Step 4: Run
	693
	694	Run: `go test ./internal/httpd/ -count=1 && go vet ./internal/httpd/`
	695	Expected: `ok`.
	696
	697	- [ ] Step 5: Commit
	698
	699	```bash
	700	git add internal/httpd/compress.go internal/httpd/compress_test.go
	701	git commit -m "httpd: gzipWriter passes a flush through
	702
	703	Ref #250"
	704	```
	705
	706	---
	707
	708	### Task 5: The build page streams a live build
	709
	710	Files:
	711	- Modify: `internal/httpd/builds.go` (`build`, ~280)
	712	- Modify: `internal/httpd/control.go` (new `runControlStream` after `runControlCode`)
	713	- Modify: `internal/web/templates/build.html`
	714
	715	Interfaces:
	716	- Consumes: `build log --follow` (Task 2), `gzipWriter.Flush` (Task 4), `Ctx.Done`.
	717	- Produces: `func (s *Server) runControlStream(u store.User, argv []string, out io.Writer, done <-chan struct{}) (msg string, code int)`; `type buildView`; `const liveLogMarker`.
	718
	719	- [ ] Step 1: Template. Replace the last content line of `build.html`:
	720
	721	```
	722	{{if .Log}}<pre class="code buildlog" tabindex="0">{{.Log}}</pre>{{else}}<p class="empty-note">no log yet</p>{{end}}
	723	```
	724
	725	with:
	726
	727	```
	728	{{if .Live}}<p class="meta">Live: the log streams here until the build ends. If it stops without a “build finished” line, reload to pick it up again. <a href="?follow=0">Show it without updates</a></p>
	729	<pre class="code buildlog" tabindex="0">{{.Log}}</pre>
	730	{{else if .Log}}<pre class="code buildlog" tabindex="0">{{.Log}}</pre>{{else}}<p class="empty-note">no log yet</p>{{end}}
	731	```
	732
	733	- [ ] Step 2: `runControlStream` in `internal/httpd/control.go` after `runControlCode` (add `io` to imports):
	734
	735	```go
	736	// runControlStream runs a command whose output is written as it is
	737	// produced: stdout goes to out, and done ends the command when the
	738	// request does. msg is stderr.
	739	func (s *Server) runControlStream(u store.User, argv []string, out io.Writer, done <-chan struct{}) (msg string, code int) {
	740	var stderr bytes.Buffer
	741	ctx := &control.Ctx{
	742	User: u,
	743	Source: "web",
	744	Scope: "full",
	745	Store: s.st,
	746	Cfg: s.cfg,
	747	Stdin: strings.NewReader(""),
	748	Stdout: out,
	749	Stderr: &stderr,
	750	ViaAPI: true,
	751	Done: done,
	752	}
	753	code = control.Dispatch(ctx, argv)
	754	return strings.TrimSpace(stderr.String()), code
	755	}
	756	```
	757
	758	- [ ] Step 3: Handler. In `internal/httpd/builds.go`, replace `build` from the `log, _, _ := s.runControl(...)` line to the end with:
	759
	760	```go
	761	v := buildView{repoPage: p, Build: b, CanWrite: s.canWriteRepo(r, p.Repo), Notice: s.takeFlash(w, r)}
	762	if (b.Status == "pending" \|\| b.Status == "running") && r.URL.Query().Get("follow") != "0" {
	763	s.streamBuild(w, r, v, viewer, n)
	764	return
	765	}
	766	v.Log, _, _ = s.runControl(viewer, []string{"build", "log", p.Repo.Path(), n})
	767	s.render(w, "build.html", v)
	768	}
	769
	770	type buildView struct {
	771	repoPage
	772	Build control.BuildOut
	773	Log string
	774	Live bool
	775	CanWrite bool
	776	Notice string
	777	}
	778
	779	// liveLogMarker stands in for the log when build.html is rendered for a
	780	// live build; streamBuild splits the page there and streams the log into
	781	// the gap. Git refs, paths and job names cannot hold the control byte.
	782	const liveLogMarker = "\x1elive-log\x1e"
	783
	784	// streamBuild writes the build page with the log following the build:
	785	// the page up to the log, then build log --follow escaped and flushed as
	786	// it arrives, then the outcome and the rest of the page.
	787	func (s Server) streamBuild(w http.ResponseWriter, r http.Request, v buildView, viewer store.User, n string) {
	788	v.Live, v.Log = true, liveLogMarker
	789	var buf bytes.Buffer
	790	if err := web.Render(&buf, "build.html", v); err != nil {
	791	http.Error(w, "template error: "+err.Error(), http.StatusInternalServerError)
	792	return
	793	}
	794	head, tail, ok := strings.Cut(buf.String(), liveLogMarker)
	795	if !ok \|\| !strings.HasPrefix(tail, "</pre>") {
	796	http.Error(w, "template error: build.html has no live log slot", http.StatusInternalServerError)
	797	return
	798	}
	799	tail = strings.TrimPrefix(tail, "</pre>")
	800
	801	h := w.Header()
	802	h.Set("Content-Type", "text/html; charset=utf-8")
	803	h.Set("Cache-Control", "no-store")
	804	h.Set("X-Accel-Buffering", "no")
	805	rc := http.NewResponseController(w)
	806	io.WriteString(w, head)
	807	rc.Flush()
	808
	809	path := v.Repo.Path()
	810	msg, code := s.runControlStream(viewer, []string{"build", "log", path, n, "--follow"},
	811	htmlStream{w: w, rc: rc}, r.Context().Done())
	812	if code == protocol.ExitDenied {
	813	// The follow cap: the stored log once, and why it is not live.
	814	log, _, _ := s.runControl(viewer, []string{"build", "log", path, n})
	815	template.HTMLEscape(w, []byte(log))
	816	}
	817	io.WriteString(w, "</pre>")
	818	switch {
	819	case code == protocol.ExitOK:
	820	var b control.BuildOut
	821	if _, ok := s.runControlInto(viewer, []string{"build", "show", path, n}, &b); ok {
	822	fmt.Fprintf(w, `<p class="notice" role="status">build finished: %s</p>`, template.HTMLEscapeString(b.Status))
	823	}
	824	case code == protocol.ExitDenied:
	825	fmt.Fprintf(w, `<p class="error" role="alert">%s</p>`, template.HTMLEscapeString(msg))
	826	}
	827	io.WriteString(w, tail)
	828	}
	829
	830	// htmlStream escapes each chunk of a streamed log into the page and
	831	// flushes it, so the browser draws it as it arrives.
	832	type htmlStream struct {
	833	w io.Writer
	834	rc *http.ResponseController
	835	}
	836
	837	func (h htmlStream) Write(p []byte) (int, error) {
	838	template.HTMLEscape(h.w, p)
	839	if err := h.rc.Flush(); err != nil {
	840	return 0, err
	841	}
	842	return len(p), nil
	843	}
	844	```
	845
	846	Add the imports `builds.go` now needs (`bytes`, `fmt`, `html/template`, `io`, `strings`, `gitbay.org/gitbay/internal/protocol`, `gitbay.org/gitbay/internal/web`) — only those not already present. If `builds.go` already imports `text/template` or another `template`, alias accordingly.
	847
	848	- [ ] Step 4: Build, vet, unit tests
	849
	850	Run: `go build ./... && go vet ./internal/httpd/ ./internal/web/ && go test ./internal/httpd/ ./internal/web/ -count=1`
	851	Expected: `ok`. (`TestMainWidthClass` needs nothing: no new template.)
	852
	853	- [ ] Step 5: Commit
	854
	855	```bash
	856	git add internal/httpd/builds.go internal/httpd/control.go internal/web/templates/build.html
	857	git commit -m "web: the build page streams a live build's log
	858
	859	Ref #250"
	860	```
	861
	862	---
	863
	864	### Task 6: e2e — follow over ssh and on the page
	865
	866	Files:
	867	- Modify: `e2e/ssh_test.go` (extract `sshCmd` from `ssh`, ~line 164)
	868	- Create: `e2e/buildfollow_test.go`
	869
	870	Interfaces:
	871	- Consumes: everything above; e2e helpers `startInstance`, `newKey`, `admin`, `ssh`, `gitEnv`, `sshURL`, `mustGit`, `httpPort`.
	872	- Produces: `func (i instance) sshCmd(key string, args ...string) exec.Cmd`.
	873
	874	- [ ] Step 1: Extract `sshCmd`. In `e2e/ssh_test.go`, split `ssh`:
	875
	876	```go
	877	// sshCmd is the ssh invocation ssh runs, for a test that reads the output
	878	// as it arrives.
	879	func (i instance) sshCmd(key string, args ...string) exec.Cmd {
	880	base := []string{
	881	"-p", fmt.Sprint(i.port),
	882	"-i", key,
	883	"-o", "IdentitiesOnly=yes",
	884	"-o", "StrictHostKeyChecking=no",
	885	"-o", "UserKnownHostsFile=" + filepath.Join(i.sshDir, "known_hosts"),
	886	"-o", "BatchMode=yes",
	887	"git@127.0.0.1",
	888	}
	889	return exec.Command("ssh", append(base, args...)...)
	890	}
	891	```
	892
	893	and have `ssh` start with `cmd := i.sshCmd(key, args...)` in place of building `base` itself.
	894
	895	- [ ] Step 2: Write the test — `e2e/buildfollow_test.go`:
	896
	897	```go
	898	package e2e
	899
	900	import (
	901	"encoding/json"
	902	"fmt"
	903	"io"
	904	"net/http"
	905	"os"
	906	"path/filepath"
	907	"strings"
	908	"testing"
	909	"time"
	910	)
	911
	912	// streamReader collects what r delivers, so a test can wait for text to
	913	// arrive while the writer is still going.
	914	type streamReader struct {
	915	ch chan []byte
	916	buf strings.Builder
	917	}
	918
	919	func newStreamReader(r io.Reader) *streamReader {
	920	s := &streamReader{ch: make(chan []byte, 16)}
	921	go func() {
	922	b := make([]byte, 4096)
	923	for {
	924	n, err := r.Read(b)
	925	if n > 0 {
	926	s.ch <- append([]byte(nil), b[:n]...)
	927	}
	928	if err != nil {
	929	close(s.ch)
	930	return
	931	}
	932	}
	933	}()
	934	return s
	935	}
	936
	937	func (s streamReader) waitFor(t testing.T, want string) string {
	938	t.Helper()
	939	deadline := time.After(20 * time.Second)
	940	for !strings.Contains(s.buf.String(), want) {
	941	select {
	942	case b, ok := <-s.ch:
	943	if !ok {
	944	t.Fatalf("stream ended before %q:\n%s", want, s.buf.String())
	945	}
	946	s.buf.Write(b)
	947	case <-deadline:
	948	t.Fatalf("no %q after 20s:\n%s", want, s.buf.String())
	949	}
	950	}
	951	return s.buf.String()
	952	}
	953
	954	// A running build is followed over ssh and on its page: output the runner
	955	// sends arrives while the build runs, and both end with the outcome.
	956	func TestBuildLogFollow(t *testing.T) {
	957	t.Parallel()
	958	inst := startInstance(t)
	959	aliceKey := inst.newKey(t, "alice")
	960	runnerKey := inst.newKey(t, "ci")
	961	inst.admin(t, "admin", "user", "create", "alice", "--key", aliceKey+".pub")
	962	inst.admin(t, "admin", "user", "create", "ci", "--key", runnerKey+".pub", "--admin")
	963	if _, _, code := inst.ssh(t, aliceKey, "", "repo", "create", "alice/app"); code != 0 {
	964	t.Fatal("repo create failed")
	965	}
	966	work := t.TempDir()
	967	env := inst.gitEnv(aliceKey)
	968	mustGit(t, work, env, "clone", inst.sshURL("alice/app"), "w")
	969	dir := filepath.Join(work, "w")
	970	os.MkdirAll(filepath.Join(dir, ".gitbay"), 0o755)
	971	os.WriteFile(filepath.Join(dir, ".gitbay", "ci.yml"), []byte("jobs:\n unit:\n steps:\n - echo fine\n"), 0o644)
	972	mustGit(t, dir, env, "checkout", "-q", "-b", "main")
	973	mustGit(t, dir, env, "add", ".")
	974	mustGit(t, dir, env, "commit", "-q", "-m", "ci")
	975	mustGit(t, dir, env, "push", "-q", "origin", "main")
	976
	977	// Claim build 1 by hand, so the test decides when output arrives.
	978	out, errOut, code := inst.ssh(t, runnerKey, "", "runner", "next", "--json")
	979	if code != 0 {
	980	t.Fatalf("runner next: %s", errOut)
	981	}
	982	var claim struct {
	983	Data struct {
	984	ID int64 `json:"id"`
	985	} `json:"data"`
	986	}
	987	if err := json.Unmarshal([]byte(out), &claim); err != nil \|\| claim.Data.ID == 0 {
	988	t.Fatalf("runner next output %q: %v", out, err)
	989	}
	990	id := fmt.Sprint(claim.Data.ID)
	991
	992	cmd := inst.sshCmd(aliceKey, "build", "log", "alice/app", "1", "--follow")
	993	stdout, err := cmd.StdoutPipe()
	994	if err != nil {
	995	t.Fatal(err)
	996	}
	997	var stderr strings.Builder
	998	cmd.Stderr = &stderr
	999	if err := cmd.Start(); err != nil {
	1000	t.Fatal(err)
	1001	}
	1002	follow := newStreamReader(stdout)
	1003
	1004	page, err := http.Get(fmt.Sprintf("http://127.0.0.1:%d/alice/app/builds/1", inst.httpPort))
	1005	if err != nil {
	1006	t.Fatal(err)
	1007	}
	1008	defer page.Body.Close()
	1009	web := newStreamReader(page.Body)
	1010	web.waitFor(t, "Live: the log streams here")
	1011
	1012	// A static render while the build runs returns at once.
	1013	static := &http.Client{Timeout: 10 * time.Second}
	1014	resp, err := static.Get(fmt.Sprintf("http://127.0.0.1:%d/alice/app/builds/1?follow=0", inst.httpPort))
	1015	if err != nil {
	1016	t.Fatalf("?follow=0 did not return: %v", err)
	1017	}
	1018	body, _ := io.ReadAll(resp.Body)
	1019	resp.Body.Close()
	1020	if strings.Contains(string(body), "Live:") {
	1021	t.Fatalf("?follow=0 rendered the live page:\n%s", body)
	1022	}
	1023
	1024	if _, errOut, code := inst.ssh(t, runnerKey, "hello from the runner <b>\n", "runner", "log", id); code != 0 {
	1025	t.Fatalf("runner log: %s", errOut)
	1026	}
	1027	follow.waitFor(t, "hello from the runner <b>\n")
	1028	web.waitFor(t, "hello from the runner <b>")
	1029
	1030	if _, errOut, code := inst.ssh(t, runnerKey, "", "runner", "done", id, "success"); code != 0 {
	1031	t.Fatalf("runner done: %s", errOut)
	1032	}
	1033	web.waitFor(t, `<p class="notice" role="status">build finished: success</p>`)
	1034	web.waitFor(t, "</html>")
	1035	if err := cmd.Wait(); err != nil {
	1036	t.Fatalf("follow exited: %v\n%s", err, stderr.String())
	1037	}
	1038	if got := strings.TrimSpace(stderr.String()); got != "build 1 success" {
	1039	t.Errorf("follow stderr %q", got)
	1040	}
	1041	}
	1042	```
	1043
	1044	- [ ] Step 3: Run it
	1045
	1046	Run: `go test ./e2e/ -run 'TestBuildLogFollow$' -count=1 -v 2>&1 \| tail -20`
	1047	Expected: `--- PASS: TestBuildLogFollow`. If `</html>` is not how the layout ends, use the last line `layout.html` renders.
	1048
	1049	- [ ] Step 4: Check the neighbours. Run `go vet ./e2e/` and the tests that use `inst.ssh` heavily and build pages: `go test ./e2e/ -run 'TestBuildCancel$\|TestControlPlaneOverBareSSH$' -count=1`.
	1050
	1051	- [ ] Step 5: Commit
	1052
	1053	```bash
	1054	git add e2e/ssh_test.go e2e/buildfollow_test.go
	1055	git commit -m "e2e: follow a running build over ssh and on its page
	1056
	1057	Ref #250"
	1058	```
	1059
	1060	---
	1061
	1062	### Task 7: Docs
	1063
	1064	Files:
	1065	- Modify: `.gitbay/wiki/Parity.org` (build rows, ~line 212)
	1066	- Modify: `.gitbay/wiki/CI.org`
	1067
	1068	- [ ] Step 1: Parity. After `\| build log \| yes \| yes \| yes \|` add (columns are cli, web, ios):
	1069
	1070	```
	1071	\| build log follow (until it ends) \| yes \| yes \| no \|
	1072	```
	1073
	1074	- [ ] Step 2: CI.org. After the paragraph that begins "Scheduled jobs run on their cron", add:
	1075
	1076	```
	1077	A running build is followed with =build log <owner/name> <n> --follow=:
	1078	the stored log, then output as the runner sends it, then the outcome
	1079	as =build <n> <status>= on stderr once the build ends. The exit code is
	1080	0 whatever the outcome. The build page does the same without
	1081	JavaScript while a build is queued or running; =?follow=0= renders it
	1082	once. An account holds at most eight follows open, and signed-out
	1083	viewers share one account's eight. Over the JSON API the command
	1084	answers when the build ends, with the whole log.
	1085	```
	1086
	1087	- [ ] Step 3: Commit
	1088
	1089	```bash
	1090	git add .gitbay/wiki/Parity.org .gitbay/wiki/CI.org
	1091	git commit -m "wiki: build log --follow
	1092
	1093	Closes #250"
	1094	```
	1095
	1096	---
	1097
	1098	## Finish
	1099
	1100	Push `build-log-follow`, open the MR with `gitbay mr create --source build-log-follow --target main --title "build log --follow, streamed to the build page" --file - < <body file>`, wait for CI, then `gitbay mr merge <n> --strategy ff` and delete the branch in both places.

docs/specs/2026-09-23-build-log-follow-design.md added +150

@@ -0,0 +1,150 @@
	1	# Following a running build
	2
	3	Closes #250. `build log <owner/name> <n> --follow` streams a build's log
	4	until the build reaches an outcome, and the web build page streams the
	5	same command without JavaScript.
	6
	7	## Problem
	8
	9	No surface can follow a running build. `build log` prints what is stored
	10	and exits; the build page renders the log once. Watching a build means
	11	re-running the command or reloading the page.
	12
	13	## Decision
	14
	15	The capability is a flag on the existing control command. The web page
	16	dispatches that command with a writer that escapes and flushes each
	17	chunk, so the CLI, stock ssh and the page share one implementation.
	18
	19	Rejected: a `Refresh` header on the build page. It re-renders the page
	20	and re-reads the whole log per reload per viewer, interrupts selection
	21	and screen readers, needs an off switch for WCAG 2.2.1, and gives only
	22	the web a way to follow.
	23
	24	## Store: waking followers
	25
	26	`Store` gains an in-memory waiter table keyed by build id:
	27
	28	- `BuildLogWait(id int64) <-chan struct{}` returns a channel closed by
	29	the next change to that build.
	30	- `AppendBuildLog`, `FinishBuild` and `CancelBuild` close and drop the
	31	build's channel after their write succeeds (`wakeBuild(id)`).
	32	- `BuildLogFrom(id, offset int64) (status string, chunk []byte, err
	33	error)` reads `status` and `substr(log, offset+1)` in one query, so a
	34	follower reads each byte once.
	35
	36	gitbayd is one process and its SSH and HTTP servers share one
	37	`*store.Store`, so an in-memory table reaches every follower. Writers in
	38	another process do not wake anyone: `gitbayd admin` subcommands, and
	39	every session under the system-sshd forced command (`gitbayd shell`),
	40	where each session is its own process. The follow loop also re-reads
	41	every 2 seconds, which bounds that case.
	42
	43	## Command
	44
	45	`build log <owner/name> <n> [--follow]`, still `ReadOnly`.
	46
	47	Without `--follow`, unchanged.
	48
	49	With `--follow`:
	50
	51	1. Write the stored log.
	52	2. Loop: take a wait channel, read from the offset, write any new bytes.
	53	If the status is no longer `pending` or `running` and the read
	54	returned nothing new, stop. Otherwise wait on the channel, the
	55	2-second timer, or `Ctx.Done`.
	56	3. Write `build <n> <status>` to stderr and exit 0, whatever the
	57	outcome. Stdout stays the log, byte for byte.
	58
	59	The wait channel is taken before the read, so a change between the read
	60	and the wait still wakes the loop.
	61
	62	`Ctx` gains `Done <-chan struct{}`, nil when the surface has none. The
	63	embedded sshd closes it when the session's channel closes (the CLI's
	64	shared connection outlives a Ctrl-C, the channel does not); `gitbayd
	65	shell` still passes nil, but its process does not end with the
	66	session: OpenSSH closes the child's pipes and sends no signal to a
	67	session with no pty, so a follow there ends at its next write, at the
	68	build's outcome, or at the queued limit below; the per-account cap is
	69	per process in that mode. httpd sets it from `r.Context()` on the web
	70	and both API endpoints. A write error also ends the loop. On `Done`
	71	the command returns `protocol.ExitFailure` with no message; nobody is
	72	reading.
	73
	74	At most 8 follows per account run at once (a counter in `control`,
	75	decremented on return). The ninth exits 4: "8 follows are already open
	76	for this account; close one and retry". Signed-out web viewers are
	77	account 0 and share the 8; the ninth gets the stored log once with the
	78	refusal under it.
	79
	80	Nothing reaps a queued build (`ReapStaleBuilds` only reaps `running`
	81	builds), and a running one is already bounded by the reaper's
	82	deadline, so a follow of a build that stays `pending` ends on its own
	83	after `followQueued` (10 minutes), writing to stderr `build <n> is
	84	still queued; nothing claimed it in 10m0s. Follow again once a runner
	85	has.` and exiting `protocol.ExitFailure`. The clock runs only while the
	86	follow has seen the build `pending`; once it sees `running` or a
	87	terminal status the limit no longer applies.
	88
	89	The CLI's `pass("log", …)` help in `cmd/gitbay/main.go` names
	90	`--follow`.
	91
	92	## Web
	93
	94	`GET /{owner}/{repo}/builds/{n}` streams when the build is `pending` or
	95	`running`, the query has no `follow=0`, and the method is `GET`. A HEAD
	96	request (the route also matches it) renders once, like `?follow=0`.
	97
	98	Streaming:
	99
	100	1. Render `build.html` into a buffer with `Log` set to a marker and
	101	`Live` true, and split the output at the marker.
	102	2. Write the head, flush.
	103	3. Dispatch `build log <repo> <n> --follow` with `Stdout` an escaping
	104	writer (`template.HTMLEscape` per chunk, then flush through
	105	`http.ResponseController`) and `Done` from the request context.
	106	4. If the request context is done (the client left), write nothing
	107	more. Otherwise write the `</pre>` that begins the tail, then, by
	108	the command's exit code: `ExitOK` reads the build and writes
	109	`<p class="notice" role="status">build finished: <status></p>`;
	110	`ExitDenied` (the follow cap) writes the stored log once above the
	111	`</pre>` and an error paragraph with the refusal, except a
	112	signed-out viewer (`viewer.ID == 0`) gets "Too many signed-out
	113	viewers are watching live builds. This is the log so far; reload to
	114	try again, or sign in." instead of the command's account-scoped
	115	wording; `ExitFailure` with a message (the queued limit) writes it
	116	as a `<p class="notice" role="status">`. Then the rest of the tail.
	117
	118	`build.html`, when `Live`, puts a line above the log: the log streams
	119	until the build ends; a stream that stops with no "build finished" line
	120	resumes on reload; and a link to `?follow=0`, the same page rendered
	121	once, as the way to stop the updates (WCAG 2.2.2). The stored log
	122	renders inside the stream from the first write, so there is no separate
	123	"no log yet" state while live.
	124
	125	`gzipWriter` gains `Flush()` (flush the gzip stream, then the underlying
	126	writer) and `Unwrap()`. The HTTP server has no `WriteTimeout`, so a long
	127	silent step does not end the response. The handler sets
	128	`X-Accel-Buffering: no` for a proxy in front of the instance.
	129
	130	## API
	131
	132	`/api/v1/cmd` and `/api/v1/read` buffer stdout, so there `--follow`
	133	returns the whole log when the build ends. Streaming a JSON response is
	134	out of scope.
	135
	136	## Tests
	137
	138	- `internal/store`: `BuildLogWait` closes on append, finish and cancel;
	139	`BuildLogFrom` returns bytes past the offset and the status.
	140	- `internal/control`: follow a running build while another goroutine
	141	appends and finishes; stdout is the full log, stderr ends with the
	142	outcome, exit 0. Cancel ends a follow. A closed `Done` ends a follow.
	143	The ninth concurrent follow exits 4.
	144	- `internal/httpd`: `gzipWriter` passes a flush through.
	145	- `e2e`: ssh `build log --follow` on a running build while the runner
	146	key appends with `runner log` and reports with `runner done`; the web
	147	page of a running build arrives complete with "build finished:
	148	success"; `?follow=0` renders without the live line.
	149
	150	Docs: the CI wiki page and Parity get the flag.

e2e/buildcancelweb_test.go +4 −4

e2e/buildfollow_test.go added +153

@@ -0,0 +1,153 @@
	1	package e2e
	2
	3	import (
	4	"encoding/json"
	5	"fmt"
	6	"io"
	7	"net/http"
	8	"os"
	9	"path/filepath"
	10	"strings"
	11	"testing"
	12	"time"
	13	)
	14
	15	// streamReader collects what r delivers, so a test can wait for text to
	16	// arrive while the writer is still going.
	17	type streamReader struct {
	18	ch chan []byte
	19	buf strings.Builder
	20	}
	21
	22	func newStreamReader(r io.Reader) *streamReader {
	23	s := &streamReader{ch: make(chan []byte, 16)}
	24	go func() {
	25	b := make([]byte, 4096)
	26	for {
	27	n, err := r.Read(b)
	28	if n > 0 {
	29	s.ch <- append([]byte(nil), b[:n]...)
	30	}
	31	if err != nil {
	32	close(s.ch)
	33	return
	34	}
	35	}
	36	}()
	37	return s
	38	}
	39
	40	func (s streamReader) waitFor(t testing.T, want string) string {
	41	t.Helper()
	42	deadline := time.After(20 * time.Second)
	43	for !strings.Contains(s.buf.String(), want) {
	44	select {
	45	case b, ok := <-s.ch:
	46	if !ok {
	47	t.Fatalf("stream ended before %q:\n%s", want, s.buf.String())
	48	}
	49	s.buf.Write(b)
	50	case <-deadline:
	51	t.Fatalf("no %q after 20s:\n%s", want, s.buf.String())
	52	}
	53	}
	54	return s.buf.String()
	55	}
	56
	57	// A running build is followed over ssh and on its page: output the runner
	58	// sends arrives while the build runs, and both end with the outcome.
	59	func TestBuildLogFollow(t *testing.T) {
	60	t.Parallel()
	61	inst := startInstance(t)
	62	aliceKey := inst.newKey(t, "alice")
	63	runnerKey := inst.newKey(t, "ci")
	64	inst.admin(t, "admin", "user", "create", "alice", "--key", aliceKey+".pub")
	65	inst.admin(t, "admin", "user", "create", "ci", "--key", runnerKey+".pub", "--admin")
	66	if _, _, code := inst.ssh(t, aliceKey, "", "repo", "create", "alice/app"); code != 0 {
	67	t.Fatal("repo create failed")
	68	}
	69	work := t.TempDir()
	70	env := inst.gitEnv(aliceKey)
	71	mustGit(t, work, env, "clone", inst.sshURL("alice/app"), "w")
	72	dir := filepath.Join(work, "w")
	73	os.MkdirAll(filepath.Join(dir, ".gitbay"), 0o755)
	74	os.WriteFile(filepath.Join(dir, ".gitbay", "ci.yml"), []byte("jobs:\n unit:\n steps:\n - echo fine\n"), 0o644)
	75	mustGit(t, dir, env, "checkout", "-q", "-b", "main")
	76	mustGit(t, dir, env, "add", ".")
	77	mustGit(t, dir, env, "commit", "-q", "-m", "ci")
	78	mustGit(t, dir, env, "push", "-q", "origin", "main")
	79
	80	// Claim build 1 by hand, so the test decides when output arrives.
	81	out, errOut, code := inst.ssh(t, runnerKey, "", "runner", "next", "--json")
	82	if code != 0 {
	83	t.Fatalf("runner next: %s", errOut)
	84	}
	85	var claim struct {
	86	Data struct {
	87	ID int64 `json:"id"`
	88	} `json:"data"`
	89	}
	90	if err := json.Unmarshal([]byte(out), &claim); err != nil \|\| claim.Data.ID == 0 {
	91	t.Fatalf("runner next output %q: %v", out, err)
	92	}
	93	id := fmt.Sprint(claim.Data.ID)
	94
	95	cmd := inst.sshCmd(aliceKey, "build", "log", "alice/app", "1", "--follow")
	96	stdout, err := cmd.StdoutPipe()
	97	if err != nil {
	98	t.Fatal(err)
	99	}
	100	var stderr strings.Builder
	101	cmd.Stderr = &stderr
	102	if err := cmd.Start(); err != nil {
	103	t.Fatal(err)
	104	}
	105	// If the test fails before the final cmd.Wait below, kill the follow
	106	// instead of leaving it running. Once that Wait has run,
	107	// cmd.ProcessState is set and this is a no-op.
	108	defer func() {
	109	if cmd.ProcessState == nil {
	110	cmd.Process.Kill()
	111	cmd.Wait()
	112	}
	113	}()
	114	follow := newStreamReader(stdout)
	115
	116	page, err := http.Get(fmt.Sprintf("http://127.0.0.1:%d/alice/app/builds/1", inst.httpPort))
	117	if err != nil {
	118	t.Fatal(err)
	119	}
	120	defer page.Body.Close()
	121	web := newStreamReader(page.Body)
	122	web.waitFor(t, "Live: the log streams here")
	123
	124	// A static render while the build runs returns at once.
	125	static := &http.Client{Timeout: 10 * time.Second}
	126	resp, err := static.Get(fmt.Sprintf("http://127.0.0.1:%d/alice/app/builds/1?follow=0", inst.httpPort))
	127	if err != nil {
	128	t.Fatalf("?follow=0 did not return: %v", err)
	129	}
	130	body, _ := io.ReadAll(resp.Body)
	131	resp.Body.Close()
	132	if strings.Contains(string(body), "Live:") {
	133	t.Fatalf("?follow=0 rendered the live page:\n%s", body)
	134	}
	135
	136	if _, errOut, code := inst.ssh(t, runnerKey, "hello from the runner <b>\n", "runner", "log", id); code != 0 {
	137	t.Fatalf("runner log: %s", errOut)
	138	}
	139	follow.waitFor(t, "hello from the runner <b>\n")
	140	web.waitFor(t, "hello from the runner <b>")
	141
	142	if _, errOut, code := inst.ssh(t, runnerKey, "", "runner", "done", id, "success"); code != 0 {
	143	t.Fatalf("runner done: %s", errOut)
	144	}
	145	web.waitFor(t, `<p class="notice" role="status">build finished: success</p>`)
	146	web.waitFor(t, "</html>")
	147	if err := cmd.Wait(); err != nil {
	148	t.Fatalf("follow exited: %v\n%s", err, stderr.String())
	149	}
	150	if got := strings.TrimSpace(stderr.String()); got != "build 1 success" {
	151	t.Errorf("follow stderr %q", got)
	152	}
	153	}

e2e/ssh_test.go +10 −4

 	return priv
 }
-// ssh runs the real OpenSSH client against the instance with the given key.
+// sshCmd is the ssh invocation ssh runs, for a test that reads the output
-func (i *instance) ssh(t *testing.T, key string, stdin string, args ...string) (string, string, int) {
+// as it arrives.
-	t.Helper()
+func (i *instance) sshCmd(key string, args ...string) *exec.Cmd {
 	base := []string{
 		"-p", fmt.Sprint(i.port),
 		"-i", key,
 		"-o", "BatchMode=yes",
 		"git@127.0.0.1",
 	}
-	cmd := exec.Command("ssh", append(base, args...)...)
+	return exec.Command("ssh", append(base, args...)...)
+}
+// ssh runs the real OpenSSH client against the instance with the given key.
+func (i *instance) ssh(t *testing.T, key string, stdin string, args ...string) (string, string, int) {
+	t.Helper()
+	cmd := i.sshCmd(key, args...)
 	if stdin != "" {
 		cmd.Stdin = strings.NewReader(stdin)
 	}

internal/control/build.go +10 −3

 		Summary: "show one build",
 		Usage:   "build show <owner/name> <n>", ReadOnly: true, Run: runBuildShow})
 	register(Command{Path: []string{"build", "log"},
-		Summary: "print a build's log",
+		Summary: "print a build's log, or follow it until the build ends",
-		Usage:   "build log <owner/name> <n>", ReadOnly: true, Run: runBuildLog})
+		Usage:   "build log <owner/name> <n> [--follow]", ReadOnly: true, Run: runBuildLog})
 	register(Command{Path: []string{"build", "jobs"},
 		Summary: "list the jobs a trigger can name",
 }
 func runBuildLog(c *Ctx, args []string) int {
-	_, b, code := buildRef(c, args)
+	f, err := parseFlags(args, flagSpec{Bools: []string{"--follow"}, MaxPos: 2, Usage: c.Cmd.Usage})
+	if err != nil {
+		return c.fail(protocol.ExitUsage, "%v", err)
+	}
+	_, b, code := buildRef(c, f.Pos)
 	if code >= 0 {
 		return code
 	}
+	if f.Has("--follow") {
+		return followBuildLog(c, b)
+	}
 	log, err := c.Store.BuildLog(b.ID)
 	if err != nil {
 		return c.fail(protocol.ExitFailure, "%v", err)

internal/control/build_test.go +5 −1

 // newQueueTestRepo returns a store with one public repo (default branch
 // "main", matching the schema default) and the uid to queue builds as.
+//
+// A real file, not ":memory:": ":memory:" gives each connection its own
+// database, so a goroutine querying while another writes (build log
+// --follow) sees an empty schema (see internal/store/contention_test.go).
 func newQueueTestRepo(t *testing.T) (*store.Store, store.Repo, int64) {
 	t.Helper()
-	st, err := store.Open(":memory:")
+	st, err := store.Open(filepath.Join(t.TempDir(), "gitbay.db"))
 	if err != nil {
 		t.Fatal(err)
 	}

internal/control/buildfollow.go added +117

@@ -0,0 +1,117 @@
	1	package control
	2
	3	import (
	4	"fmt"
	5	"sync"
	6	"time"
	7
	8	"gitbay.org/gitbay/internal/protocol"
	9	"gitbay.org/gitbay/internal/store"
	10	)
	11
	12	// maxFollows is how many build log follows one account holds open at
	13	// once. Signed-out web viewers are account 0 and share it.
	14	const maxFollows = 8
	15
	16	var (
	17	// followPoll bounds a wait with no wake. A write from another process
	18	// (gitbayd admin, or any session under gitbayd shell) wakes nobody;
	19	// this is how its bytes still arrive.
	20	followPoll = 2 * time.Second
	21	// followSettle is how long a follow keeps reading after the build has
	22	// an outcome: a cancel appends its line after the status changes, and
	23	// a cancelled runner's stream runs on until its next check.
	24	followSettle = time.Second
	25	// followQueued bounds how long a follow waits on a build that stays
	26	// pending: nothing reaps a queued build (ReapStaleBuilds only reaps
	27	// running builds), and a running one is already bounded by the
	28	// reaper's deadline, so a follow needs its own limit for the queued
	29	// case or it never ends.
	30	followQueued = 10 * time.Minute
	31	)
	32
	33	var (
	34	followMu sync.Mutex
	35	follows = map[int64]int{}
	36	)
	37
	38	func takeFollow(uid int64) bool {
	39	followMu.Lock()
	40	defer followMu.Unlock()
	41	if follows[uid] >= maxFollows {
	42	return false
	43	}
	44	follows[uid]++
	45	return true
	46	}
	47
	48	func dropFollow(uid int64) {
	49	followMu.Lock()
	50	defer followMu.Unlock()
	51	if follows[uid]--; follows[uid] <= 0 {
	52	delete(follows, uid)
	53	}
	54	}
	55
	56	// followBuildLog writes the build's log as it grows and returns once the
	57	// build has an outcome and its last bytes are written. The outcome goes
	58	// to stderr, so stdout is the log byte for byte.
	59	func followBuildLog(c *Ctx, b store.Build) int {
	60	if !takeFollow(c.User.ID) {
	61	return c.fail(protocol.ExitDenied, "%d follows are already open for this account; close one and retry", maxFollows)
	62	}
	63	defer dropFollow(c.User.ID)
	64
	65	var off int64
	66	var settleBy time.Time
	67	var queuedSince time.Time
	68	for {
	69	wake := c.Store.BuildLogWait(b.ID)
	70	status, chunk, err := c.Store.BuildLogFrom(b.ID, off)
	71	if err != nil {
	72	return c.fail(protocol.ExitFailure, "%v", err)
	73	}
	74	if len(chunk) > 0 {
	75	if _, err := c.Stdout.Write(chunk); err != nil {
	76	return protocol.ExitFailure
	77	}
	78	off += int64(len(chunk))
	79	}
	80	if status == "pending" {
	81	if queuedSince.IsZero() {
	82	queuedSince = time.Now()
	83	}
	84	} else {
	85	queuedSince = time.Time{}
	86	}
	87	wait := followPoll
	88	if status == "pending" {
	89	left := queuedSince.Add(followQueued).Sub(time.Now())
	90	if left <= 0 {
	91	fmt.Fprintf(c.Stderr, "build %d is still queued; nothing claimed it in %v. Follow again once a runner has.\n", b.Number, followQueued)
	92	return protocol.ExitFailure
	93	}
	94	wait = min(wait, left)
	95	}
	96	if status != "pending" && status != "running" {
	97	if settleBy.IsZero() {
	98	settleBy = time.Now().Add(followSettle)
	99	}
	100	left := time.Until(settleBy)
	101	if left <= 0 && len(chunk) == 0 {
	102	fmt.Fprintf(c.Stderr, "build %d %s\n", b.Number, status)
	103	return protocol.ExitOK
	104	}
	105	wait = min(wait, max(left, 0))
	106	}
	107	t := time.NewTimer(wait)
	108	select {
	109	case <-wake:
	110	case <-t.C:
	111	case <-c.Done:
	112	t.Stop()
	113	return protocol.ExitFailure
	114	}
	115	t.Stop()
	116	}
	117	}

internal/control/buildfollow_test.go added +190

@@ -0,0 +1,190 @@
	1	package control
	2
	3	import (
	4	"bytes"
	5	"strings"
	6	"sync"
	7	"testing"
	8	"time"
	9
	10	"gitbay.org/gitbay/internal/protocol"
	11	"gitbay.org/gitbay/internal/store"
	12	)
	13
	14	// syncBuffer is a bytes.Buffer guarded by a mutex, safe for a test to poll
	15	// while the follow goroutine is still writing to it.
	16	type syncBuffer struct {
	17	mu sync.Mutex
	18	buf bytes.Buffer
	19	}
	20
	21	func (b *syncBuffer) Write(p []byte) (int, error) {
	22	b.mu.Lock()
	23	defer b.mu.Unlock()
	24	return b.buf.Write(p)
	25	}
	26
	27	func (b *syncBuffer) String() string {
	28	b.mu.Lock()
	29	defer b.mu.Unlock()
	30	return b.buf.String()
	31	}
	32
	33	// follow starts build log --follow on build 1 of repo and returns the
	34	// buffers and a channel carrying the exit code.
	35	func follow(t testing.T, st store.Store, uid int64, repo store.Repo, done <-chan struct{}) (syncBuffer, syncBuffer, chan int) {
	36	t.Helper()
	37	u, err := st.UserByID(uid)
	38	if err != nil {
	39	t.Fatal(err)
	40	}
	41	var out, errOut syncBuffer
	42	c := &Ctx{User: u, Scope: "full", Store: st, Stdin: strings.NewReader(""),
	43	Stdout: &out, Stderr: &errOut, Done: done}
	44	res := make(chan int, 1)
	45	go func() { res <- Dispatch(c, []string{"build", "log", repo.Path(), "1", "--follow"}) }()
	46	return &out, &errOut, res
	47	}
	48
	49	func waitExit(t *testing.T, res chan int) int {
	50	t.Helper()
	51	select {
	52	case code := <-res:
	53	return code
	54	case <-time.After(10 * time.Second):
	55	t.Fatal("follow did not end")
	56	return -1
	57	}
	58	}
	59
	60	func shortFollowTimers(t *testing.T) {
	61	settle, poll, queued := followSettle, followPoll, followQueued
	62	followSettle, followPoll = 200time.Millisecond, 50time.Millisecond
	63	t.Cleanup(func() { followSettle, followPoll, followQueued = settle, poll, queued })
	64	}
	65
	66	// The follow prints the stored log, then what arrives, and ends with the
	67	// outcome on stderr once the build finishes.
	68	func TestBuildLogFollow(t *testing.T) {
	69	shortFollowTimers(t)
	70	st, repo, uid := newQueueTestRepo(t)
	71	id, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true)
	72	if err != nil {
	73	t.Fatal(err)
	74	}
	75	st.AppendBuildLog(id, []byte("queued\n"))
	76	out, errOut, res := follow(t, st, uid, repo, nil)
	77
	78	if _, ok, err := st.ClaimBuild([]int64{repo.ID}, false); err != nil \|\| !ok {
	79	t.Fatalf("claim: %v %v", ok, err)
	80	}
	81	st.AppendBuildLog(id, []byte("step one\n"))
	82	st.AppendBuildLog(id, []byte("step two\n"))
	83	if err := st.FinishBuild(id, "success"); err != nil {
	84	t.Fatal(err)
	85	}
	86	if code := waitExit(t, res); code != protocol.ExitOK {
	87	t.Fatalf("exit %d: %s", code, errOut)
	88	}
	89	if got := out.String(); got != "queued\nstep one\nstep two\n" {
	90	t.Errorf("stdout %q", got)
	91	}
	92	if got := strings.TrimSpace(errOut.String()); got != "build 1 success" {
	93	t.Errorf("stderr %q", got)
	94	}
	95	}
	96
	97	// A cancel ends the follow, and the line the cancel appends after the
	98	// status change still arrives.
	99	func TestBuildLogFollowCancel(t *testing.T) {
	100	shortFollowTimers(t)
	101	st, repo, uid := newQueueTestRepo(t)
	102	id, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true)
	103	if err != nil {
	104	t.Fatal(err)
	105	}
	106	out, errOut, res := follow(t, st, uid, repo, nil)
	107	if err := st.CancelBuild(id); err != nil {
	108	t.Fatal(err)
	109	}
	110	st.AppendBuildLog(id, []byte("cancelled by alice before a runner claimed it\n"))
	111	if code := waitExit(t, res); code != protocol.ExitOK {
	112	t.Fatalf("exit %d: %s", code, errOut)
	113	}
	114	if !strings.Contains(out.String(), "cancelled by alice") {
	115	t.Errorf("the cancel line did not arrive: %q", out)
	116	}
	117	if got := strings.TrimSpace(errOut.String()); got != "build 1 cancelled" {
	118	t.Errorf("stderr %q", got)
	119	}
	120	}
	121
	122	// Closing Done ends a follow of a build that is still running, even while
	123	// it is blocked waiting for the next change: the build gets a line, the
	124	// follower is confirmed to have read it (so it is back in its wait), then
	125	// Done closes.
	126	func TestBuildLogFollowDone(t *testing.T) {
	127	shortFollowTimers(t)
	128	st, repo, uid := newQueueTestRepo(t)
	129	id, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true)
	130	if err != nil {
	131	t.Fatal(err)
	132	}
	133	st.AppendBuildLog(id, []byte("step one\n"))
	134	done := make(chan struct{})
	135	out, _, res := follow(t, st, uid, repo, done)
	136
	137	deadline := time.After(2 * time.Second)
	138	for !strings.Contains(out.String(), "step one") {
	139	select {
	140	case <-deadline:
	141	t.Fatal("follow never read the appended line")
	142	case <-time.After(10 * time.Millisecond):
	143	}
	144	}
	145	close(done)
	146	if code := waitExit(t, res); code != protocol.ExitFailure {
	147	t.Fatalf("exit %d, want %d", code, protocol.ExitFailure)
	148	}
	149	}
	150
	151	// A build that stays pending ends its own follow: nothing reaps a queued
	152	// build, so the follow must give up on its own.
	153	func TestBuildLogFollowQueued(t *testing.T) {
	154	shortFollowTimers(t)
	155	followQueued = 150 * time.Millisecond
	156	st, repo, uid := newQueueTestRepo(t)
	157	if _, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true); err != nil {
	158	t.Fatal(err)
	159	}
	160	_, errOut, res := follow(t, st, uid, repo, nil)
	161	if code := waitExit(t, res); code != protocol.ExitFailure {
	162	t.Fatalf("exit %d, want %d: %s", code, protocol.ExitFailure, errOut)
	163	}
	164	if !strings.Contains(errOut.String(), "still queued") {
	165	t.Errorf("stderr %q", errOut)
	166	}
	167	}
	168
	169	// An account holding maxFollows is refused another.
	170	func TestBuildLogFollowCap(t *testing.T) {
	171	st, repo, uid := newQueueTestRepo(t)
	172	if _, err := st.CreateBuild(repo.ID, "unit", "abc", "main", `["true"]`, "", "", true); err != nil {
	173	t.Fatal(err)
	174	}
	175	followMu.Lock()
	176	follows[uid] = maxFollows
	177	followMu.Unlock()
	178	t.Cleanup(func() {
	179	followMu.Lock()
	180	delete(follows, uid)
	181	followMu.Unlock()
	182	})
	183	_, errOut, res := follow(t, st, uid, repo, nil)
	184	if code := waitExit(t, res); code != protocol.ExitDenied {
	185	t.Fatalf("exit %d, want %d", code, protocol.ExitDenied)
	186	}
	187	if !strings.Contains(errOut.String(), "8 follows are already open") {
	188	t.Errorf("stderr %q", errOut)
	189	}
	190	}

internal/control/control.go +4

 	// Cmd is the command being run, set by Dispatch, so a usage error can
 	// print the registered usage rather than a copy of it.
 	Cmd Command
+	// Done, when the surface has one, closes when nobody is reading any
+	// more: the SSH channel closed or the HTTP request ended. A command
+	// that runs until something happens (build log --follow) stops on it.
+	Done <-chan struct{}
 }
 // usage reports a bad invocation with the command's registered usage,

internal/httpd/api.go +1

	@@ -73,6 +73,7 @@ func (s Server) apiCmd(w http.ResponseWriter, r http.Request) {
73	JSON: true,	73	JSON: true,
74	ViaAPI: true,	74	ViaAPI: true,
75	ReadOnly: scope == "read",	75	ReadOnly: scope == "read",
		76	Done: r.Context().Done(),
76	}	77	}
77	code := control.Dispatch(ctx, req.Argv)	78	code := control.Dispatch(ctx, req.Argv)
78		79

internal/httpd/apiread.go +1

	@@ -62,6 +62,7 @@ func (s Server) apiRead(w http.ResponseWriter, r http.Request) {
62	JSON: true,	62	JSON: true,
63	ViaAPI: true,	63	ViaAPI: true,
64	ReadOnly: true,	64	ReadOnly: true,
		65	Done: r.Context().Done(),
65	}	66	}
66	code := control.Dispatch(ctx, argv)	67	code := control.Dispatch(ctx, argv)
67		68

internal/httpd/buildpages_test.go +5 −11

 func TestBuildPageRendersCommandOutput(t *testing.T) {
 	var sb strings.Builder
-	err := web.Render(&sb, "build.html", struct {
+	err := web.Render(&sb, "build.html", buildView{
-		repoPage
+		repoPage: testRepoPage(),
-		Build    control.BuildOut
+		Build: control.BuildOut{
-		Log      string
-		CanWrite bool
-		Notice   string
-	}{
-		testRepoPage(),
-		control.BuildOut{
 			Number: 60, Job: "build", Status: "success",
 			SHA: "ff6271a9d4570cd46f169091637a9d2e40ad5c2b", Ref: "cli-coverage",
 			CreatedAt: "2026-08-28T04:42:54Z", FinishedAt: "2026-08-28T04:43:06Z",
 		},
-		"step 1 ok",
+		Log:      "step 1 ok",
-		true, "",
+		CanWrite: true,
 	})
 	if err != nil {
 		t.Fatalf("render: %v", err)

internal/httpd/builds.go +102 −8

	@@ -1,12 +1,20 @@
1	package httpd	1	package httpd
2		2
3	import (	3	import (
		4	"bytes"
		5	"fmt"
		6	"html/template"
		7	"io"
4	"net/http"	8	"net/http"
5	"net/url"	9	"net/url"
6	"slices"	10	"slices"
7	"strconv"	11	"strconv"
		12	"strings"
8		13
9	"gitbay.org/gitbay/internal/control"	14	"gitbay.org/gitbay/internal/control"
		15	"gitbay.org/gitbay/internal/protocol"
		16	"gitbay.org/gitbay/internal/store"
		17	"gitbay.org/gitbay/internal/web"
10	)	18	)
11		19
12	// buildFilter is the builds page's GET filter: branch, status and job,	20	// buildFilter is the builds page's GET filter: branch, status and job,
	@@ -295,13 +303,99 @@ func (s Server) build(w http.ResponseWriter, r http.Request) {
295	s.notFound(w, r)	303	s.notFound(w, r)
296	return	304	return
297	}	305	}
298	log, _, _ := s.runControl(viewer, []string{"build", "log", p.Repo.Path(), n})	306	v := buildView{repoPage: p, Build: b, CanWrite: s.canWriteRepo(r, p.Repo), Notice: s.takeFlash(w, r)}
		307	if (b.Status == "pending" \|\| b.Status == "running") && r.URL.Query().Get("follow") != "0" && r.Method == http.MethodGet {
		308	s.streamBuild(w, r, v, viewer, n)
		309	return
		310	}
		311	v.Log, _, _ = s.runControl(viewer, []string{"build", "log", p.Repo.Path(), n})
		312	s.render(w, "build.html", v)
		313	}
299		314
300	s.render(w, "build.html", struct {	315	type buildView struct {
301	repoPage	316	repoPage
302	Build control.BuildOut	317	Build control.BuildOut
303	Log string	318	Log string
304	CanWrite bool	319	Live bool
305	Notice string	320	CanWrite bool
306	}{p, b, log, s.canWriteRepo(r, p.Repo), s.takeFlash(w, r)})	321	Notice string
		322	}
		323
		324	// liveLogMarker stands in for the log when build.html is rendered for a
		325	// live build; streamBuild splits the page there and streams the log into
		326	// the gap. Git refs, paths and job names cannot hold the control byte.
		327	const liveLogMarker = "\x1elive-log\x1e"
		328
		329	// streamBuild writes the build page with the log following the build:
		330	// the page up to the log, then build log --follow escaped and flushed as
		331	// it arrives, then the outcome and the rest of the page.
		332	func (s Server) streamBuild(w http.ResponseWriter, r http.Request, v buildView, viewer store.User, n string) {
		333	v.Live, v.Log = true, liveLogMarker
		334	var buf bytes.Buffer
		335	if err := web.Render(&buf, "build.html", v); err != nil {
		336	http.Error(w, "template error: "+err.Error(), http.StatusInternalServerError)
		337	return
		338	}
		339	head, tail, ok := strings.Cut(buf.String(), liveLogMarker)
		340	if !ok \|\| !strings.HasPrefix(tail, "</pre>") {
		341	http.Error(w, "template error: build.html has no live log slot", http.StatusInternalServerError)
		342	return
		343	}
		344	tail = strings.TrimPrefix(tail, "</pre>")
		345
		346	h := w.Header()
		347	h.Set("Content-Type", "text/html; charset=utf-8")
		348	h.Set("Cache-Control", "no-store")
		349	h.Set("X-Accel-Buffering", "no")
		350	rc := http.NewResponseController(w)
		351	io.WriteString(w, head)
		352	rc.Flush()
		353
		354	path := v.Repo.Path()
		355	msg, code := s.runControlStream(viewer, []string{"build", "log", path, n, "--follow"},
		356	htmlStream{w: w, rc: rc}, r.Context().Done())
		357	if r.Context().Err() != nil {
		358	// The client left; nothing more to write.
		359	return
		360	}
		361	if code == protocol.ExitDenied {
		362	// The follow cap: the stored log once, and why it is not live.
		363	log, _, _ := s.runControl(viewer, []string{"build", "log", path, n})
		364	template.HTMLEscape(w, []byte(log))
		365	}
		366	io.WriteString(w, "</pre>")
		367	switch {
		368	case code == protocol.ExitOK:
		369	var b control.BuildOut
		370	if _, ok := s.runControlInto(viewer, []string{"build", "show", path, n}, &b); ok {
		371	fmt.Fprintf(w, `<p class="notice" role="status">build finished: %s</p>`, template.HTMLEscapeString(b.Status))
		372	}
		373	case code == protocol.ExitDenied:
		374	if viewer.ID == 0 {
		375	msg = "Too many signed-out viewers are watching live builds. This is the log so far; reload to try again, or sign in."
		376	}
		377	fmt.Fprintf(w, `<p class="error" role="alert">%s</p>`, template.HTMLEscapeString(msg))
		378	case code == protocol.ExitFailure && msg != "":
		379	fmt.Fprintf(w, `<p class="notice" role="status">%s</p>`, template.HTMLEscapeString(msg))
		380	}
		381	io.WriteString(w, tail)
		382	}
		383
		384	// htmlStream escapes each chunk of a streamed log into the page and
		385	// flushes it, so the browser draws it as it arrives.
		386	type htmlStream struct {
		387	w io.Writer
		388	rc *http.ResponseController
		389	}
		390
		391	func (h htmlStream) Write(p []byte) (int, error) {
		392	var buf bytes.Buffer
		393	template.HTMLEscape(&buf, p)
		394	if _, err := h.w.Write(buf.Bytes()); err != nil {
		395	return 0, err
		396	}
		397	if err := h.rc.Flush(); err != nil {
		398	return 0, err
		399	}
		400	return len(p), nil
307	}	401	}

internal/httpd/compress.go +24

	@@ -83,3 +83,27 @@ func (g *gzipWriter) Close() {
83	g.gz.Close()	83	g.gz.Close()
84	}	84	}
85	}	85	}
		86
		87	// Flush sends what the gzip stream holds, then flushes the connection, so
		88	// a streamed page reaches the browser as it is written.
		89	func (g *gzipWriter) Flush() {
		90	g.FlushError()
		91	}
		92
		93	// FlushError is Flush with the error a failed flush produces.
		94	// http.ResponseController.Flush prefers this over Flush when both are
		95	// implemented, so a write that fails partway through a stream is reported
		96	// instead of silently dropped.
		97	func (g *gzipWriter) FlushError() error {
		98	if !g.decided {
		99	g.decide(http.StatusOK)
		100	}
		101	if g.gz != nil {
		102	if err := g.gz.Flush(); err != nil {
		103	return err
		104	}
		105	}
		106	return http.NewResponseController(g.ResponseWriter).Flush()
		107	}
		108
		109	func (g *gzipWriter) Unwrap() http.ResponseWriter { return g.ResponseWriter }

internal/httpd/compress_test.go +29

	@@ -6,6 +6,7 @@ import (
6	"io"	6	"io"
7	"net/http"	7	"net/http"
8	"net/http/httptest"	8	"net/http/httptest"
		9	"strings"
9	"testing"	10	"testing"
10		11
11	"gitbay.org/gitbay/internal/config"	12	"gitbay.org/gitbay/internal/config"
	@@ -79,3 +80,31 @@ func TestBinaryResponsesPassThrough(t *testing.T) {
79	t.Fatalf("git transport touched: %q %q", rec.Header().Get("Content-Encoding"), rec.Body.String())	80	t.Fatalf("git transport touched: %q %q", rec.Header().Get("Content-Encoding"), rec.Body.String())
80	}	81	}
81	}	82	}
		83
		84	// A flush mid-response reaches the connection with what was written so
		85	// far decodable, which is what lets a page stream through gzip.
		86	func TestGzipWriterFlushes(t *testing.T) {
		87	rec := httptest.NewRecorder()
		88	h := compressed(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		89	w.Header().Set("Content-Type", "text/html; charset=utf-8")
		90	io.WriteString(w, "<p>first</p>")
		91	if err := http.NewResponseController(w).Flush(); err != nil {
		92	t.Fatalf("flush: %v", err)
		93	}
		94	if !rec.Flushed {
		95	t.Fatal("the flush did not reach the connection")
		96	}
		97	zr, err := gzip.NewReader(bytes.NewReader(rec.Body.Bytes()))
		98	if err != nil {
		99	t.Fatalf("gzip header: %v", err)
		100	}
		101	got, _ := io.ReadAll(zr) // no trailer yet: ends in ErrUnexpectedEOF
		102	if !strings.Contains(string(got), "<p>first</p>") {
		103	t.Fatalf("flushed body decodes to %q", got)
		104	}
		105	io.WriteString(w, "<p>second</p>")
		106	}))
		107	req := httptest.NewRequest("GET", "/", nil)
		108	req.Header.Set("Accept-Encoding", "gzip")
		109	h.ServeHTTP(rec, req)
		110	}

internal/httpd/control.go +22

	@@ -3,6 +3,7 @@ package httpd
3	import (	3	import (
4	"bytes"	4	"bytes"
5	"encoding/json"	5	"encoding/json"
		6	"io"
6	"net/http"	7	"net/http"
7	"strings"	8	"strings"
8		9
	@@ -50,6 +51,27 @@ func (s *Server) runControlCode(u store.User, argv []string) (out string, msg st
50	return stdout.String(), m, code	51	return stdout.String(), m, code
51	}	52	}
52		53
		54	// runControlStream runs a command whose output is written as it is
		55	// produced: stdout goes to out, and done ends the command when the
		56	// request does. msg is stderr.
		57	func (s *Server) runControlStream(u store.User, argv []string, out io.Writer, done <-chan struct{}) (msg string, code int) {
		58	var stderr bytes.Buffer
		59	ctx := &control.Ctx{
		60	User: u,
		61	Source: "web",
		62	Scope: "full",
		63	Store: s.st,
		64	Cfg: s.cfg,
		65	Stdin: strings.NewReader(""),
		66	Stdout: out,
		67	Stderr: &stderr,
		68	ViaAPI: true,
		69	Done: done,
		70	}
		71	code = control.Dispatch(ctx, argv)
		72	return strings.TrimSpace(stderr.String()), code
		73	}
		74
53	// done finishes a form action by exit code: back to the page on success,	75	// done finishes a form action by exit code: back to the page on success,
54	// the 404 page when the thing does not exist, and back to the page with	76	// the 404 page when the thing does not exist, and back to the page with
55	// the message for anything else. A refusal is feedback on the page a	77	// the message for anything else. A refusal is feedback on the page a

internal/sshd/sshd.go +15 −4

 				continue
 			}
 			req.Reply(true, nil)
-			code := s.runExec(sconn, ch, payload.Command)
+			// x/crypto closes reqs when the client closes the channel. That
+			// is how a follow learns nobody is reading: the CLI's shared
+			// connection outlives a Ctrl-C, the channel does not.
+			done := make(chan struct{})
+			go func() {
+				for r := range reqs {
+					r.Reply(false, nil)
+				}
+				close(done)
+			}()
+			code := s.runExec(sconn, ch, payload.Command, done)
 			sendExit(ch, code)
 			return
 		case "shell":
 	ch.SendRequest("exit-status", false, ssh.Marshal(&msg))
 }
-func (s *Server) runExec(sconn *ssh.ServerConn, ch ssh.Channel, cmdline string) int {
+func (s *Server) runExec(sconn *ssh.ServerConn, ch ssh.Channel, cmdline string, done <-chan struct{}) int {
 	ext := sconn.Permissions.Extensions
 	if blob := ext["anon-key"]; blob != "" {
 		return s.runAnonymous(ch, blob, cmdline)
 		return protocol.ExitDenied
 	}
 	_ = s.st.TouchSSHKey(keyID)
-	return Exec(s.cfg, s.st, user, ext["scope"], ext["key-fp"], cmdline, ch, ch, ch.Stderr())
+	return Exec(s.cfg, s.st, user, ext["scope"], ext["key-fp"], cmdline, ch, ch, ch.Stderr(), done)
 }
 // runAnonymous handles a session from an unregistered key: the register
 // single dispatch path shared by the embedded listener and the system-sshd
 // forced command (gitbayd shell).
 func Exec(cfg config.Config, st *store.Store, user store.User, scope, source, cmdline string,
-	stdin io.Reader, stdout, stderr io.Writer) int {
+	stdin io.Reader, stdout, stderr io.Writer, done <-chan struct{}) int {
 	if user.Disabled {
 		fmt.Fprintln(stderr, "this account is disabled; contact the instance admin")
 		return protocol.ExitDenied
 		Stdin:  stdin,
 		Stdout: stdout,
 		Stderr: stderr,
+		Done:   done,
 	}
 	return control.Dispatch(ctx, argv)
 }

internal/store/builds.go +48

	@@ -233,6 +233,7 @@ func (s *Store) AppendBuildLog(id int64, chunk []byte) error {
233	return err	233	return err
234	}	234	}
235	if n, _ := res.RowsAffected(); n > 0 {	235	if n, _ := res.RowsAffected(); n > 0 {
		236	s.wakeBuild(id)
236	return nil	237	return nil
237	}	238	}
238	// Over the cap. The bounds match exactly once: appending the notice puts	239	// Over the cap. The bounds match exactly once: appending the notice puts
	@@ -241,6 +242,9 @@ func (s *Store) AppendBuildLog(id int64, chunk []byte) error {
241	UPDATE builds SET log = log \|\| ?	242	UPDATE builds SET log = log \|\| ?
242	WHERE id = ? AND length(log) >= ? AND length(log) < ?`,	243	WHERE id = ? AND length(log) >= ? AND length(log) < ?`,
243	truncNotice, id, MaxBuildLog, MaxBuildLog+len(truncNotice))	244	truncNotice, id, MaxBuildLog, MaxBuildLog+len(truncNotice))
		245	if err == nil {
		246	s.wakeBuild(id)
		247	}
244	return err	248	return err
245	}	249	}
246		250
	@@ -255,6 +259,7 @@ func (s *Store) FinishBuild(id int64, status string) error {
255	if n, _ := res.RowsAffected(); n == 0 {	259	if n, _ := res.RowsAffected(); n == 0 {
256	return ErrNotFound	260	return ErrNotFound
257	}	261	}
		262	s.wakeBuild(id)
258	return nil	263	return nil
259	}	264	}
260		265
	@@ -331,6 +336,48 @@ func (s *Store) BuildLog(id int64) ([]byte, error) {
331	return log, err	336	return log, err
332	}	337	}
333		338
		339	// BuildLogWait returns a channel closed by the next append to, finish of
		340	// or cancel of the build. Take it before reading, so a change between the
		341	// read and the wait still wakes the reader. Only this process's writes
		342	// wake it.
		343	func (s *Store) BuildLogWait(id int64) <-chan struct{} {
		344	s.logMu.Lock()
		345	defer s.logMu.Unlock()
		346	if s.logWait == nil {
		347	s.logWait = map[int64]chan struct{}{}
		348	}
		349	ch, ok := s.logWait[id]
		350	if !ok {
		351	ch = make(chan struct{})
		352	s.logWait[id] = ch
		353	}
		354	return ch
		355	}
		356
		357	func (s *Store) wakeBuild(id int64) {
		358	s.logMu.Lock()
		359	defer s.logMu.Unlock()
		360	if ch, ok := s.logWait[id]; ok {
		361	close(ch)
		362	delete(s.logWait, id)
		363	}
		364	}
		365
		366	// BuildLogFrom returns the build's status and its log past offset bytes,
		367	// read together so a terminal status comes with every byte before it.
		368	// The cast matters: \|\| stores the log as text, and substr on text counts
		369	// characters.
		370	func (s *Store) BuildLogFrom(id, offset int64) (string, []byte, error) {
		371	var status string
		372	var chunk []byte
		373	err := s.DB.QueryRow(`SELECT status, substr(CAST(log AS BLOB), ?) FROM builds WHERE id = ?`,
		374	offset+1, id).Scan(&status, &chunk)
		375	if errors.Is(err, sql.ErrNoRows) {
		376	return "", nil, ErrNotFound
		377	}
		378	return status, chunk, err
		379	}
		380
334	// LatestBuild returns the newest build for a repo, optionally narrowed to	381	// LatestBuild returns the newest build for a repo, optionally narrowed to
335	// one job. It is what a status badge reports.	382	// one job. It is what a status badge reports.
336	func (s *Store) LatestBuild(repoID int64, job string) (Build, error) {	383	func (s *Store) LatestBuild(repoID int64, job string) (Build, error) {
	@@ -399,6 +446,7 @@ func (s *Store) CancelBuild(id int64) error {
399	if n, _ := res.RowsAffected(); n == 0 {	446	if n, _ := res.RowsAffected(); n == 0 {
400	return ErrNotFound	447	return ErrNotFound
401	}	448	}
		449	s.wakeBuild(id)
402	return nil	450	return nil
403	}	451	}
404		452

internal/store/builds_test.go +101

	@@ -426,3 +426,104 @@ func TestClaimBuildSkipsUntrustedUnlessAsked(t *testing.T) {
426	t.Fatalf("untrusted claim: err=%v ok=%v number=%d, want %d", err, ok, b.Number, forkBuild)	426	t.Fatalf("untrusted claim: err=%v ok=%v number=%d, want %d", err, ok, b.Number, forkBuild)
427	}	427	}
428	}	428	}
		429
		430	// A follower's channel closes on each kind of change to its build, and
		431	// only its build.
		432	func TestBuildLogWaitWakes(t *testing.T) {
		433	s := open(t)
		434	if err := s.MigrateUp(); err != nil {
		435	t.Fatal(err)
		436	}
		437	uid, err := s.CreateUser("cmc", true)
		438	if err != nil {
		439	t.Fatal(err)
		440	}
		441	if _, err := s.CreateRepo("user", uid, "orgo", "public"); err != nil {
		442	t.Fatal(err)
		443	}
		444	newBuild := func() int64 {
		445	t.Helper()
		446	id, err := s.CreateBuild(1, "test", "abc123", "main", `["true"]`, "", "", true)
		447	if err != nil {
		448	t.Fatal(err)
		449	}
		450	return id
		451	}
		452	closed := func(ch <-chan struct{}) bool {
		453	select {
		454	case <-ch:
		455	return true
		456	default:
		457	return false
		458	}
		459	}
		460
		461	a, b := newBuild(), newBuild()
		462	wa, wb := s.BuildLogWait(a), s.BuildLogWait(b)
		463	if err := s.AppendBuildLog(a, []byte("x")); err != nil {
		464	t.Fatal(err)
		465	}
		466	if !closed(wa) {
		467	t.Error("append did not wake its build")
		468	}
		469	if closed(wb) {
		470	t.Error("append woke another build")
		471	}
		472
		473	mustClaim(t, s, 1) // claims a, the oldest
		474	wa = s.BuildLogWait(a)
		475	if err := s.FinishBuild(a, "success"); err != nil {
		476	t.Fatal(err)
		477	}
		478	if !closed(wa) {
		479	t.Error("finish did not wake")
		480	}
		481
		482	if err := s.CancelBuild(b); err != nil {
		483	t.Fatal(err)
		484	}
		485	if !closed(wb) {
		486	t.Error("cancel did not wake")
		487	}
		488	}
		489
		490	// Offsets are bytes, not characters: \|\| stores the log as text, and a
		491	// multibyte character must not shift where the next read starts.
		492	func TestBuildLogFrom(t *testing.T) {
		493	s := open(t)
		494	if err := s.MigrateUp(); err != nil {
		495	t.Fatal(err)
		496	}
		497	uid, err := s.CreateUser("cmc", true)
		498	if err != nil {
		499	t.Fatal(err)
		500	}
		501	if _, err := s.CreateRepo("user", uid, "orgo", "public"); err != nil {
		502	t.Fatal(err)
		503	}
		504	id, err := s.CreateBuild(1, "test", "abc123", "main", `["true"]`, "", "", true)
		505	if err != nil {
		506	t.Fatal(err)
		507	}
		508	first := "héllo — ok\n"
		509	for _, c := range []string{first, "wörld\n"} {
		510	if err := s.AppendBuildLog(id, []byte(c)); err != nil {
		511	t.Fatal(err)
		512	}
		513	}
		514	status, all, err := s.BuildLogFrom(id, 0)
		515	if err != nil \|\| status != "pending" \|\| string(all) != first+"wörld\n" {
		516	t.Fatalf("from 0: %q %q %v", status, all, err)
		517	}
		518	_, rest, err := s.BuildLogFrom(id, int64(len(first)))
		519	if err != nil \|\| string(rest) != "wörld\n" {
		520	t.Fatalf("from %d: %q %v", len(first), rest, err)
		521	}
		522	_, none, err := s.BuildLogFrom(id, int64(len(all)))
		523	if err != nil \|\| len(none) != 0 {
		524	t.Fatalf("from the end: %q %v", none, err)
		525	}
		526	if _, _, err := s.BuildLogFrom(9999, 0); err != ErrNotFound {
		527	t.Fatalf("missing build: %v", err)
		528	}
		529	}

internal/store/store.go +6

 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 	"modernc.org/sqlite"
 )
 type Store struct {
 	DB *sql.DB
+	// logWait holds one channel per build someone is following, closed
+	// by the next change to that build's row (BuildLogWait).
+	logMu   sync.Mutex
+	logWait map[int64]chan struct{}
 }
 // Open opens (creating if needed) the database at path with WAL mode and

internal/web/templates/build.html +3 −1

	@@ -12,5 +12,7 @@
12	{{end}}	12	{{end}}
13	</div>	13	</div>
14	<p class="meta">{{.Build.Job}} on {{.Build.Ref}} · <code><a href="/{{.Repo.OwnerName}}/{{.Repo.Name}}/commit/{{.Build.SHA}}">{{printf "%.10s" .Build.SHA}}</a></code> · queued {{when .Build.CreatedAt}}{{if .Build.FinishedAt}} · finished {{when .Build.FinishedAt}}{{end}}</p>	14	<p class="meta">{{.Build.Job}} on {{.Build.Ref}} · <code><a href="/{{.Repo.OwnerName}}/{{.Repo.Name}}/commit/{{.Build.SHA}}">{{printf "%.10s" .Build.SHA}}</a></code> · queued {{when .Build.CreatedAt}}{{if .Build.FinishedAt}} · finished {{when .Build.FinishedAt}}{{end}}</p>
15	{{if .Log}}<pre class="code buildlog" tabindex="0">{{.Log}}</pre>{{else}}<p class="empty-note">no log yet</p>{{end}}	15	{{if .Live}}<p class="meta">Live: the log streams here until the build ends. If it stops without a “build finished” line, reload to pick it up again. <a href="?follow=0">Show it without updates</a></p>
		16	<pre class="code buildlog" tabindex="0">{{.Log}}</pre>
		17	{{else if .Log}}<pre class="code buildlog" tabindex="0">{{.Log}}</pre>{{else}}<p class="empty-note">no log yet</p>{{end}}
16	{{end}}	18	{{end}}

	@@ -46,13 +46,13 @@ func TestBuildCancelWeb(t *testing.T) {
46	build1 := inst.base() + "/alice/app/builds/1"	46	build1 := inst.base() + "/alice/app/builds/1"
47		47
48	// Build 1 is queued: the control is on the page, for someone with	48	// Build 1 is queued: the control is on the page, for someone with
49	// write access.	49	// write access. follow=0: a live build's page streams until it ends.
50	_, body := browserGet(t, alice, build1)	50	_, body := browserGet(t, alice, build1+"?follow=0")
51	if !strings.Contains(body, `action="/alice/app/builds/1/cancel"`) {	51	if !strings.Contains(body, `action="/alice/app/builds/1/cancel"`) {
52	t.Fatalf("no cancel control on a queued build:\n%s", body)	52	t.Fatalf("no cancel control on a queued build:\n%s", body)
53	}	53	}
54	// A reader gets no control.	54	// A reader gets no control.
55	_, anon := browserGet(t, newBrowser(t), build1)	55	_, anon := browserGet(t, newBrowser(t), build1+"?follow=0")
56	if strings.Contains(anon, "/cancel") {	56	if strings.Contains(anon, "/cancel") {
57	t.Fatal("anonymous visitor sees the cancel control")	57	t.Fatal("anonymous visitor sees the cancel control")
58	}	58	}
	@@ -78,7 +78,7 @@ func TestBuildCancelWeb(t *testing.T) {
78	t.Fatalf("runner claim: %s", out)	78	t.Fatalf("runner claim: %s", out)
79	}	79	}
80	build2 := inst.base() + "/alice/app/builds/2"	80	build2 := inst.base() + "/alice/app/builds/2"
81	_, body = browserGet(t, alice, build2)	81	_, body = browserGet(t, alice, build2+"?follow=0")
82	if !strings.Contains(body, "running") {	82	if !strings.Contains(body, "running") {
83	t.Fatalf("build 2 not running:\n%s", body)	83	t.Fatalf("build 2 not running:\n%s", body)
84	}	84	}