refactor(learn): split src/learn.sh into a src/learn/ module

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.

[Chemaclass]

🤔 Background

Related #931

Fourth module under ADR-010, after runner (#924), coverage (#925) and reports (#937). src/learn.sh was the largest remaining flat file at 1213 lines. Responsibility map posted on #931 before any code moved.

💡 Changes

File	Contents
learn/progress.sh	LEARN_PROGRESS_FILE, mark_completed, is_completed, show_progress, reset_progress
learn/session.sh	LEARN_TEMP_DIR, init, cleanup, create_example_file, run_lesson_test
learn/lessons/*.sh	one file per lesson (10 files, 64–139 lines each)
learn/menu.sh	print_menu, start

Layering from all 37 internal call edges: progress ← session ← lessons ← menu. Every lesson calls exactly create_example_file and run_lesson_test; no lesson calls another, so the ten are independent and each is one file. bashunit::learn::start remains the only external entry point.

lessons/ as a subdirectory keeps the three plumbing files visible instead of buried among ten curriculum files. That makes this depth-3 — the first real use of the nesting #932 pinned with a regression test.

⚠️ One correction to the issue, and a trap it caused

The issue's table lists this file as 82 functions. Only 20 are real — the other 62 are sample code inside heredocs (the tutorial's example tests), counted because they sit at line-start in heredoc bodies.

That mattered. Segmenting on a ^}$ closing brace — which worked for the previous three modules — terminates lesson bodies early here at a brace inside rendered sample code, and would have split functions across files. I caught it on a coverage check (large bogus gaps inside lesson bodies) and re-derived boundaries from the next function's start, which heredocs cannot affect. Every new file is bash -n clean.

✅ Verification

A relocation: non-blank line multiset differs only by new shebangs, module headers and source lines; 20 functions before and after; the sorted code content of the built artifact is identical; bash build.sh bin -v → ✅ Build verified ✅.

tests/unit/learn_test.sh sources the module by path to isolate $HOME (LEARN_PROGRESS_FILE is a readonly resolved at source time). Its hardcoded src/learn.sh is repointed at src/learn/index.sh — this surfaced as 14 red tests before the fix, not a behaviour break.

The file-wide # shellcheck disable=SC2016 moved to the seven lesson files that actually need it. Lines over 120 bytes are box-drawing UTF-8 and under 120 characters, so no .editorconfig rule is needed.

Green: sequential · --parallel · --parallel --simple --strict · make sa · make lint · CI-mode ShellCheck · bashunit learn smoke-tested end-to-end.