Harden template-loader error handling and reduce duplication

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.

[zevorn]

Summary

• Remove spurious blank stderr line from load_template when template file is missing (was echo "" >&2 before the warning message, polluting stderr output)
• Add awk exit code propagation in render_template — if the awk substitution engine fails, the error is now surfaced to stderr and the function returns non-zero instead of silently producing empty output
• Extract _emit_fallback helper to eliminate duplicated fallback emission logic in load_and_render_safe (same 5-line pattern was repeated twice)
• Guard append_template against appending empty content when the additional template is missing (previously appended an empty line unconditionally)
• Extend validate_template_dir to check all 5 required subdirectories (block, codex, claude, plan, pr-loop) — previously only checked the first 3

All existing tests pass (43/43 template-loader tests, 104/104 template-reference checks).

Test plan

• bash tests/test-template-loader.sh — all 43 tests pass
• bash tests/test-template-references.sh — all 104 checks pass, 0 failures
• Verify no behavioral regression in RLCR loop stop hook flow
• Verify load_and_render_safe fallback still works correctly in validators

[SihaoLiu]

Merged into dev branch via local merge (commit 1862329). Template-loader hardening applied.